[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/game/quest_handler.cpp

@@ -469,7 +469,7 @@ void QuestHandler::registerOpcodes(DispatchTable& table) {
                         owner_.questCompleteCallback_(questId, it->title);
                     }
                     // Play quest-complete sound
-                    if (auto* renderer = core::Application::getInstance().getRenderer()) {
+                    if (auto* renderer = owner_.services().renderer) {
                         if (auto* sfx = renderer->getUiSoundManager())
                             sfx->playQuestComplete();
                     }
@@ -1092,7 +1092,7 @@ void QuestHandler::acceptQuest() {
     pendingQuestAcceptNpcGuids_[questId] = npcGuid;
 
     // Play quest-accept sound
-    if (auto* renderer = core::Application::getInstance().getRenderer()) {
+    if (auto* renderer = owner_.services().renderer) {
         if (auto* sfx = renderer->getUiSoundManager())
             sfx->playQuestActivate();
     }