refactor(log): migra game/scenes i game/ui a Log::

- logo_scene, title_scene, intro_scene, room_fsm: missatges de
  cicle d'escena com a Log::info amb tag "scene" o "RoomFsm".
  Eliminats els TODO obsolets sobre el logger pendent.
- game_scene (16 logs): events del bus (LEVEL COMPLETE, PLAYER HIT,
  PLAYER KILLED) com a info; transicions de ROOM com a info; warns
  als casos d'àudio absent o música no arrencada.
- hud (3 logs): init i events com a info.

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

source/game/scenes/intro_scene.cpp

@@ -4,7 +4,6 @@
 
 #include <algorithm>
 #include <cstdint>
-#include <iostream>
 #include <string>
 #include <utility>
 
@@ -20,13 +19,12 @@
 #include "game/scenes/scene_flow.hpp"
 #include "utils/defaults.hpp"
 #include "utils/defines.hpp"
+#include "utils/log.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
@@ -34,7 +32,7 @@ namespace {
 IntroScene::IntroScene(std::shared_ptr<Text> font, DebugConfig::StartingPlayers starting_players)
     : font_(std::move(font)),
       starting_players_(starting_players) {
-    std::cout << "[scene] " << SCENE_NAME << " start (players=" << DebugConfig::toString(starting_players_) << ")\n";
+    Log::info("scene", "{} start (players={})", SCENE_NAME, DebugConfig::toString(starting_players_));
 }
 
 IntroScene::~IntroScene() = default;