refactor: eliminar Options::physics/audio/gameplay (codi mort)

Aquestes tres seccions s'estaven carregant del YAML, parsejant,
validant i escrivint, però cap d'elles tenia consumidor en runtime:
- Options::physics: l'únic call-site era un std::cout informatiu a
  director.cpp:109. Ship/Enemy/Bullet llegeixen Defaults::Physics
  directament.
- Options::audio: explícitament desacoblat (audio.hpp:22-25) — la
  font de configuració era Defaults::Audio via Audio::Config.
- Options::gameplay: zero readers. Els arrays són compile-time.

Esborrats:
- Structs Physics/Gameplay/Music/Sound/Audio i les globals.
- Defaults a init(), helpers loadXxxConfigFromYaml, secció escrita
  a saveToFile, crides al loadFromFile.
- La línia "Física: rotation=..." del console output del Director.

Es manté Options::window i Options::rendering (sí utilitzats).

Hallazgo #21 de CODE_REVIEW.md (opció a: borrar).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

source/core/system/director.cpp

@@ -9,10 +9,6 @@
 #include <iostream>
 #include <memory>
 
-#include "debug_overlay.hpp"
-#include "scene.hpp"
-#include "scene_context.hpp"
-#include "global_events.hpp"
 #include "core/audio/audio.hpp"
 #include "core/audio/audio_adapter.hpp"
 #include "core/defaults.hpp"
@@ -22,11 +18,15 @@
 #include "core/resources/resource_helper.hpp"
 #include "core/resources/resource_loader.hpp"
 #include "core/utils/path_utils.hpp"
+#include "debug_overlay.hpp"
+#include "game/options.hpp"
 #include "game/scenes/game_scene.hpp"
 #include "game/scenes/logo_scene.hpp"
 #include "game/scenes/title_scene.hpp"
-#include "game/options.hpp"
+#include "global_events.hpp"
 #include "project.h"
+#include "scene.hpp"
+#include "scene_context.hpp"
 
 #ifndef _WIN32
 #include <pwd.h>
@@ -106,8 +106,6 @@ Director::Director(std::vector<std::string> const& args) {
         std::cout << "Configuración carregada\n";
         std::cout << "  Finestra: " << Options::window.width << "×"
                   << Options::window.height << '\n';
-        std::cout << "  Física: rotation=" << Options::physics.rotation_speed
-                  << " rad/s\n";
         std::cout << "  Input: " << Input::get()->getNumGamepads()
                   << " gamepad(s) detectat(s)\n";
     }
@@ -291,8 +289,7 @@ auto Director::buildScene(SceneType type, SDLManager& sdl, SceneContext& context
     }
 }
 
-void Director::runFrameLoop(Scene& scene, SDLManager& sdl, SceneContext& context,
-                            System::DebugOverlay& debug_overlay) {
+void Director::runFrameLoop(Scene& scene, SDLManager& sdl, SceneContext& context, System::DebugOverlay& debug_overlay) {
     SDL_Event event;
     Uint64 last_time = SDL_GetTicks();
 
@@ -315,8 +312,7 @@ void Director::runFrameLoop(Scene& scene, SDLManager& sdl, SceneContext& context
             if (GlobalEvents::handle(event, sdl, context)) {
                 continue;
             }
-            if (event.type == SDL_EVENT_KEY_DOWN
-                && event.key.scancode == SDL_SCANCODE_F11) {
+            if (event.type == SDL_EVENT_KEY_DOWN && event.key.scancode == SDL_SCANCODE_F11) {
                 debug_overlay.toggle();
                 continue;
             }