feat(scenes): afegir placeholders LogoScene/TitleScene/IntroScene

Tres escenes de 5 s cadascuna, activables al flux que precedeix GameScene.
Classes separades (sense base comuna) perquè divergiran quan es
desenvolupi contingut real.

Avancen per timeout o per qualsevol tecla no reservada. Les tecles
reservades (F1-F12, Escape) són les declarades a data/input/keys.yaml i
mantenen el seu comportament habitual via GlobalInputs. La
classificació viu a Placeholder::isReservedScancode, i KeyConfig exposa
bindings() per enumerar-les sense duplicar la llista.

Encara no integrats al Director: això es fa al següent commit quan
s'afegeix el selector d'escena inicial.

source/game/scenes/intro_scene.cpp

@@ -0,0 +1,85 @@
+#include "game/scenes/intro_scene.hpp"
+
+#include <SDL3/SDL.h>
+
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <string>
+#include <utility>
+
+#include "core/input/global_inputs.hpp"
+#include "core/rendering/notifier.hpp"
+#include "core/rendering/render_info.hpp"
+#include "core/rendering/screen.hpp"
+#include "core/rendering/text.hpp"
+#include "core/system/event_buffer.hpp"
+#include "game/options.hpp"
+#include "game/scenes/placeholder_input.hpp"
+#include "game/ui/ui_palette.hpp"
+#include "utils/defaults.hpp"
+#include "utils/defines.hpp"
+
+namespace {
+
+    constexpr int NAME_Y_OFFSET = -8;
+    constexpr int TIMER_Y_OFFSET = 8;
+    // TODO: migrar a un logger unificat quan es decideixi (veure INC-03 a
+    // docs/audit-core-rendering.md).
+    const char* const SCENE_NAME = "INTRO";
+
+}  // namespace
+
+IntroScene::IntroScene(std::shared_ptr<Text> font, SceneFactory next_factory)
+    : font_(std::move(font)),
+      next_factory_(std::move(next_factory)) {
+    std::cout << "[scene] " << SCENE_NAME << " start\n";
+}
+
+IntroScene::~IntroScene() = default;
+
+void IntroScene::update(int delta_ms) {
+    GlobalInputs::update(delta_ms);
+    if (GlobalInputs::wantsQuit()) {
+        wants_quit_ = true;
+        return;
+    }
+
+    timer_ms_ -= delta_ms;
+
+    const bool SKIPPED = std::ranges::any_of(EventBuffer::events, [](const SDL_Event& ev) {
+        return ev.type == SDL_EVENT_KEY_DOWN && !Placeholder::isReservedScancode(ev.key.scancode);
+    });
+
+    if ((timer_ms_ <= 0 || SKIPPED) && next_factory_) {
+        next_scene_ = next_factory_();
+    }
+
+    Notifier::get().update(delta_ms);
+    RenderInfo::get().update(delta_ms, Options::buildRenderInfoFrame(UiColor::RENDER_INFO_TEXT, UiColor::RENDER_INFO_SHADOW));
+}
+
+void IntroScene::render() {
+    constexpr std::uint32_t BLACK_ARGB = 0xFF000000U;
+    Screen::get().fillRect(0, 0, GameCanvas::WIDTH, GameCanvas::HEIGHT, BLACK_ARGB);
+
+    if (font_) {
+        const int SECS_LEFT = std::max(1, (timer_ms_ + 999) / 1000);
+        font_->writeDX(Text::CENTER_FLAG | Text::COLOR_FLAG,
+            GameCanvas::CENTER_X,
+            GameCanvas::CENTER_Y + NAME_Y_OFFSET,
+            SCENE_NAME,
+            1,
+            Defaults::UI::NOTIFICATION_TEXT);
+        font_->writeDX(Text::CENTER_FLAG | Text::COLOR_FLAG,
+            GameCanvas::CENTER_X,
+            GameCanvas::CENTER_Y + TIMER_Y_OFFSET,
+            std::to_string(SECS_LEFT),
+            1,
+            Defaults::UI::NOTIFICATION_TEXT);
+    }
+
+    Notifier::get().render();
+    RenderInfo::get().render();
+    Screen::get().present();
+}

source/game/scenes/intro_scene.hpp

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <functional>
+#include <memory>
+
+#include "core/scene/scene.hpp"
+
+class Text;
+
+// Escena placeholder de la introducció. Com la resta de placeholders, durada
+// fixa i skip amb tecla no reservada; quan expira encadena a la factory
+// injectada (en producció: GameScene).
+class IntroScene : public Scene {
+   public:
+    using SceneFactory = std::function<std::unique_ptr<Scene>()>;
+
+    static constexpr int DURATION_MS = 5000;
+
+    IntroScene(std::shared_ptr<Text> font, SceneFactory next_factory);
+    ~IntroScene() override;
+
+    void update(int delta_ms) override;
+    void render() override;
+
+   private:
+    std::shared_ptr<Text> font_;
+    SceneFactory next_factory_;
+    int timer_ms_{DURATION_MS};
+};

source/game/scenes/logo_scene.cpp

@@ -0,0 +1,86 @@
+#include "game/scenes/logo_scene.hpp"
+
+#include <SDL3/SDL.h>
+
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <string>
+#include <utility>
+
+#include "core/input/global_inputs.hpp"
+#include "core/rendering/notifier.hpp"
+#include "core/rendering/render_info.hpp"
+#include "core/rendering/screen.hpp"
+#include "core/rendering/text.hpp"
+#include "core/system/event_buffer.hpp"
+#include "game/options.hpp"
+#include "game/scenes/placeholder_input.hpp"
+#include "game/ui/ui_palette.hpp"
+#include "utils/defaults.hpp"
+#include "utils/defines.hpp"
+
+namespace {
+
+    constexpr int NAME_Y_OFFSET = -8;
+    constexpr int TIMER_Y_OFFSET = 8;
+    // TODO: migrar a un logger unificat quan es decideixi (veure INC-03 a
+    // docs/audit-core-rendering.md). De moment std::cout per rastrejar el
+    // flux d'escenes als smoke runs.
+    const char* const SCENE_NAME = "LOGO";
+
+}  // namespace
+
+LogoScene::LogoScene(std::shared_ptr<Text> font, SceneFactory next_factory)
+    : font_(std::move(font)),
+      next_factory_(std::move(next_factory)) {
+    std::cout << "[scene] " << SCENE_NAME << " start\n";
+}
+
+LogoScene::~LogoScene() = default;
+
+void LogoScene::update(int delta_ms) {
+    GlobalInputs::update(delta_ms);
+    if (GlobalInputs::wantsQuit()) {
+        wants_quit_ = true;
+        return;
+    }
+
+    timer_ms_ -= delta_ms;
+
+    const bool SKIPPED = std::ranges::any_of(EventBuffer::events, [](const SDL_Event& ev) {
+        return ev.type == SDL_EVENT_KEY_DOWN && !Placeholder::isReservedScancode(ev.key.scancode);
+    });
+
+    if ((timer_ms_ <= 0 || SKIPPED) && next_factory_) {
+        next_scene_ = next_factory_();
+    }
+
+    Notifier::get().update(delta_ms);
+    RenderInfo::get().update(delta_ms, Options::buildRenderInfoFrame(UiColor::RENDER_INFO_TEXT, UiColor::RENDER_INFO_SHADOW));
+}
+
+void LogoScene::render() {
+    constexpr std::uint32_t BLACK_ARGB = 0xFF000000U;
+    Screen::get().fillRect(0, 0, GameCanvas::WIDTH, GameCanvas::HEIGHT, BLACK_ARGB);
+
+    if (font_) {
+        const int SECS_LEFT = std::max(1, (timer_ms_ + 999) / 1000);
+        font_->writeDX(Text::CENTER_FLAG | Text::COLOR_FLAG,
+            GameCanvas::CENTER_X,
+            GameCanvas::CENTER_Y + NAME_Y_OFFSET,
+            SCENE_NAME,
+            1,
+            Defaults::UI::NOTIFICATION_TEXT);
+        font_->writeDX(Text::CENTER_FLAG | Text::COLOR_FLAG,
+            GameCanvas::CENTER_X,
+            GameCanvas::CENTER_Y + TIMER_Y_OFFSET,
+            std::to_string(SECS_LEFT),
+            1,
+            Defaults::UI::NOTIFICATION_TEXT);
+    }
+
+    Notifier::get().render();
+    RenderInfo::get().render();
+    Screen::get().present();
+}

source/game/scenes/logo_scene.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <functional>
+#include <memory>
+
+#include "core/scene/scene.hpp"
+
+class Text;
+
+// Escena placeholder del logotip. Durada fixa (5 s) o skip amb qualsevol tecla
+// no reservada. Quan expira, encadena amb la `SceneFactory` que se li injecta
+// al ctor — així l'escena no coneix el tipus concret de la següent, i es pot
+// exercir en tests sense arrossegar GameScene.
+class LogoScene : public Scene {
+   public:
+    using SceneFactory = std::function<std::unique_ptr<Scene>()>;
+
+    static constexpr int DURATION_MS = 5000;
+
+    LogoScene(std::shared_ptr<Text> font, SceneFactory next_factory);
+    ~LogoScene() override;
+
+    void update(int delta_ms) override;
+    void render() override;
+
+   private:
+    std::shared_ptr<Text> font_;
+    SceneFactory next_factory_;
+    int timer_ms_{DURATION_MS};
+};

source/game/scenes/placeholder_input.cpp

@@ -0,0 +1,15 @@
+#include "game/scenes/placeholder_input.hpp"
+
+#include <algorithm>
+
+#include "core/input/key_config.hpp"
+
+namespace Placeholder {
+
+    auto isReservedScancode(SDL_Scancode sc) -> bool {
+        if (sc == SDL_SCANCODE_UNKNOWN) { return false; }
+        const auto& bindings = KeyConfig::get().bindings();
+        return std::ranges::any_of(bindings, [sc](const auto& kv) { return kv.second == sc; });
+    }
+
+}  // namespace Placeholder

source/game/scenes/placeholder_input.hpp

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <SDL3/SDL.h>
+
+// Helper per als placeholders del flux LOGO → TITLE → INTRO → GAME. Les escenes
+// placeholder avancen amb qualsevol tecla excepte les registrades a KeyConfig
+// (F1–F12, Escape), que mantenen el seu comportament habitual via GlobalInputs.
+namespace Placeholder {
+
+    // Retorna true si el scancode coincideix amb alguna tecla declarada al
+    // KeyConfig::get() (les carregades de data/input/keys.yaml). Si KeyConfig
+    // no s'ha carregat, totes les consultes retornaran SDL_SCANCODE_UNKNOWN i
+    // aquesta funció tornarà false, de manera que el test/smoke no depèn de
+    // l'estat global de la configuració.
+    [[nodiscard]] auto isReservedScancode(SDL_Scancode sc) -> bool;
+
+}  // namespace Placeholder

source/game/scenes/title_scene.cpp

@@ -0,0 +1,85 @@
+#include "game/scenes/title_scene.hpp"
+
+#include <SDL3/SDL.h>
+
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
+#include <string>
+#include <utility>
+
+#include "core/input/global_inputs.hpp"
+#include "core/rendering/notifier.hpp"
+#include "core/rendering/render_info.hpp"
+#include "core/rendering/screen.hpp"
+#include "core/rendering/text.hpp"
+#include "core/system/event_buffer.hpp"
+#include "game/options.hpp"
+#include "game/scenes/placeholder_input.hpp"
+#include "game/ui/ui_palette.hpp"
+#include "utils/defaults.hpp"
+#include "utils/defines.hpp"
+
+namespace {
+
+    constexpr int NAME_Y_OFFSET = -8;
+    constexpr int TIMER_Y_OFFSET = 8;
+    // TODO: migrar a un logger unificat quan es decideixi (veure INC-03 a
+    // docs/audit-core-rendering.md).
+    const char* const SCENE_NAME = "TITLE";
+
+}  // namespace
+
+TitleScene::TitleScene(std::shared_ptr<Text> font, SceneFactory next_factory)
+    : font_(std::move(font)),
+      next_factory_(std::move(next_factory)) {
+    std::cout << "[scene] " << SCENE_NAME << " start\n";
+}
+
+TitleScene::~TitleScene() = default;
+
+void TitleScene::update(int delta_ms) {
+    GlobalInputs::update(delta_ms);
+    if (GlobalInputs::wantsQuit()) {
+        wants_quit_ = true;
+        return;
+    }
+
+    timer_ms_ -= delta_ms;
+
+    const bool SKIPPED = std::ranges::any_of(EventBuffer::events, [](const SDL_Event& ev) {
+        return ev.type == SDL_EVENT_KEY_DOWN && !Placeholder::isReservedScancode(ev.key.scancode);
+    });
+
+    if ((timer_ms_ <= 0 || SKIPPED) && next_factory_) {
+        next_scene_ = next_factory_();
+    }
+
+    Notifier::get().update(delta_ms);
+    RenderInfo::get().update(delta_ms, Options::buildRenderInfoFrame(UiColor::RENDER_INFO_TEXT, UiColor::RENDER_INFO_SHADOW));
+}
+
+void TitleScene::render() {
+    constexpr std::uint32_t BLACK_ARGB = 0xFF000000U;
+    Screen::get().fillRect(0, 0, GameCanvas::WIDTH, GameCanvas::HEIGHT, BLACK_ARGB);
+
+    if (font_) {
+        const int SECS_LEFT = std::max(1, (timer_ms_ + 999) / 1000);
+        font_->writeDX(Text::CENTER_FLAG | Text::COLOR_FLAG,
+            GameCanvas::CENTER_X,
+            GameCanvas::CENTER_Y + NAME_Y_OFFSET,
+            SCENE_NAME,
+            1,
+            Defaults::UI::NOTIFICATION_TEXT);
+        font_->writeDX(Text::CENTER_FLAG | Text::COLOR_FLAG,
+            GameCanvas::CENTER_X,
+            GameCanvas::CENTER_Y + TIMER_Y_OFFSET,
+            std::to_string(SECS_LEFT),
+            1,
+            Defaults::UI::NOTIFICATION_TEXT);
+    }
+
+    Notifier::get().render();
+    RenderInfo::get().render();
+    Screen::get().present();
+}

source/game/scenes/title_scene.hpp

@@ -0,0 +1,30 @@
+#pragma once
+
+#include <functional>
+#include <memory>
+
+#include "core/scene/scene.hpp"
+
+class Text;
+
+// Escena placeholder del títol. Mateix comportament que LogoScene — duració
+// fixa de 5 s i skip amb tecla no reservada —, però classe separada perquè
+// quan divergeixi en contingut real (menú, seleccions, animacions) creixi en
+// el seu propi fitxer sense haver de refactoritzar cap base comuna.
+class TitleScene : public Scene {
+   public:
+    using SceneFactory = std::function<std::unique_ptr<Scene>()>;
+
+    static constexpr int DURATION_MS = 5000;
+
+    TitleScene(std::shared_ptr<Text> font, SceneFactory next_factory);
+    ~TitleScene() override;
+
+    void update(int delta_ms) override;
+    void render() override;
+
+   private:
+    std::shared_ptr<Text> font_;
+    SceneFactory next_factory_;
+    int timer_ms_{DURATION_MS};
+};