[refactor] Break Application::getInstance() from GameHandler

Introduce `GameServices` struct — an explicit dependency bundle that
`Application` populates and passes to `GameHandler` at construction time.
Eliminates all 47 hidden `Application::getInstance()` calls in
`src/game/*.cpp`, completing SOLID-D (dependency-inversion) cleanup.

Changes:
- New `include/game/game_services.hpp` — `struct GameServices` carrying
  pointers to `Renderer`, `AssetManager`, `ExpansionRegistry`, and two
  taxi-mount display IDs
- `GameHandler(GameServices&)` replaces default constructor; exposes
  `services() const` accessor for domain handlers
- `Application` holds `game::GameServices gameServices_`; populates it
  after all subsystems are created, then constructs `GameHandler`
  (fixes latent init-order bug: `GameHandler` was previously created
  before `AssetManager` / `ExpansionRegistry`)
- `game_handler.cpp`: duplicate `isActiveExpansion` / `isClassicLikeExpansion` /
  `isPreWotlk` anonymous-namespace helpers removed; `game_utils.hpp`
  included instead
- All domain handlers (`InventoryHandler`, `SpellHandler`, `MovementHandler`,
  `CombatHandler`, `QuestHandler`, `SocialHandler`, `WardenHandler`) replace
  `Application::getInstance().getXxx()` with `owner_.services().xxx`

src/core/application.cpp

@@ -256,7 +256,6 @@ bool Application::initialize() {
 
     // Create subsystems
     authHandler = std::make_unique<auth::AuthHandler>();
-    gameHandler = std::make_unique<game::GameHandler>();
     world = std::make_unique<game::World>();
 
     // Create and initialize expansion registry
@@ -268,6 +267,14 @@ bool Application::initialize() {
     // Create asset manager
     assetManager = std::make_unique<pipeline::AssetManager>();
 
+    // Populate game services — all subsystems now available
+    gameServices_.renderer = renderer.get();
+    gameServices_.assetManager = assetManager.get();
+    gameServices_.expansionRegistry = expansionRegistry_.get();
+
+    // Create game handler with explicit service dependencies
+    gameHandler = std::make_unique<game::GameHandler>(gameServices_);
+
     // Try to get WoW data path from environment variable
     const char* dataPathEnv = std::getenv("WOW_DATA_PATH");
     std::string dataPath = dataPathEnv ? dataPathEnv : "./Data";
@@ -5657,6 +5664,8 @@ void Application::buildCreatureDisplayLookups() {
 
     gryphonDisplayId_ = resolveDisplayIdForExactPath("Creature\\Gryphon\\Gryphon.m2");
     wyvernDisplayId_  = resolveDisplayIdForExactPath("Creature\\Wyvern\\Wyvern.m2");
+    gameServices_.gryphonDisplayId = gryphonDisplayId_;
+    gameServices_.wyvernDisplayId  = wyvernDisplayId_;
     LOG_INFO("Taxi mount displayIds: gryphon=", gryphonDisplayId_, " wyvern=", wyvernDisplayId_);
 
     // CharHairGeosets.dbc: maps (race, sex, hairStyleId) → skinSectionId for hair mesh