refactor(core): decompose Application::setupUICallbacks() into 7 domain handlers

Extract ~1,700 lines / 60+ inline [this]-capturing lambdas from the monolithic
Application::setupUICallbacks() into 7 focused callback handler classes following
the ToastManager/ChatPanel::setupCallbacks() pattern already in the codebase.

New handlers (include/core/ + src/core/):
  - NPCInteractionCallbackHandler  NPC greeting/farewell/vendor/aggro voice
  - AudioCallbackHandler           Music, positional sound, level-up, achievement, LFG
  - EntitySpawnCallbackHandler     Creature/player/GO spawn, despawn, move, state
  - AnimationCallbackHandler       Death, respawn, combat, emotes, charge, sprint, vehicle
  - TransportCallbackHandler       Mount, taxi, transport spawn/move
  - WorldEntryCallbackHandler      World entry, unstuck, hearthstone, bind point
  - UIScreenCallbackHandler        Auth, realm selection, char selection/creation/deletion

application.cpp:  4,462 → 2,791 lines  (−1,671)
setupUICallbacks: ~1,700 → ~50 lines (thin orchestrator)

Deduplication:
  resolveSoundEntryPath()   — was 3× copy-paste of SoundEntries.dbc lookup
  resolveNpcVoiceType()     — was 4× copy-paste of display-ID→voice detection
  precacheNearbyTiles()     — was 3× copy-paste of 17×17 tile loop
  4 helper lambdas          — promoted to private methods on WorldEntryCallbackHandler

State migration out of Application:
  charge* (6 vars)          → AnimationCallbackHandler
  hearth*/worldEntry*/taxi* → WorldEntryCallbackHandler
  pendingCreatedCharacterName_ → UIScreenCallbackHandler

Bug fixes:
  - Duplicate `namespace core {` in application.hpp caused wowee::std pollution
  - AppState forward decl in ui_screen_callback_handler.hpp was at wrong scope
  - world_loader.cpp accessed moved member vars directly via friend; now uses handler API

src/core/npc_interaction_callback_handler.cpp

@@ -0,0 +1,84 @@
+#include "core/npc_interaction_callback_handler.hpp"
+#include "core/entity_spawner.hpp"
+#include "core/coordinates.hpp"
+#include "core/logger.hpp"
+#include "rendering/renderer.hpp"
+#include "rendering/character_renderer.hpp"
+#include "rendering/animation/animation_ids.hpp"
+#include "game/game_handler.hpp"
+#include "audio/audio_coordinator.hpp"
+#include "audio/npc_voice_manager.hpp"
+
+namespace wowee { namespace core {
+
+NPCInteractionCallbackHandler::NPCInteractionCallbackHandler(
+    EntitySpawner& entitySpawner,
+    rendering::Renderer* renderer,
+    game::GameHandler& gameHandler,
+    audio::AudioCoordinator* audioCoordinator)
+    : entitySpawner_(entitySpawner)
+    , renderer_(renderer)
+    , gameHandler_(gameHandler)
+    , audioCoordinator_(audioCoordinator)
+{
+}
+
+audio::VoiceType NPCInteractionCallbackHandler::resolveNpcVoiceType(uint64_t guid) const {
+    audio::VoiceType voiceType = audio::VoiceType::GENERIC;
+    auto entity = gameHandler_.getEntityManager().getEntity(guid);
+    if (entity && entity->getType() == game::ObjectType::UNIT) {
+        auto unit = std::static_pointer_cast<game::Unit>(entity);
+        uint32_t displayId = unit->getDisplayId();
+        voiceType = entitySpawner_.detectVoiceTypeFromDisplayId(displayId);
+    }
+    return voiceType;
+}
+
+void NPCInteractionCallbackHandler::setupCallbacks() {
+    // NPC greeting callback - play voice line
+    gameHandler_.setNpcGreetingCallback([this](uint64_t guid, const glm::vec3& position) {
+        // Play NPC_WELCOME animation on the NPC
+        if (renderer_) {
+            auto* cr = renderer_->getCharacterRenderer();
+            if (cr) {
+                uint32_t instanceId = entitySpawner_.getCreatureInstanceId(guid);
+                if (instanceId != 0) cr->playAnimation(instanceId, rendering::anim::NPC_WELCOME, false);
+            }
+        }
+        if (audioCoordinator_ && audioCoordinator_->getNpcVoiceManager()) {
+            // Convert canonical to render coords for 3D audio
+            glm::vec3 renderPos = core::coords::canonicalToRender(position);
+            audio::VoiceType voiceType = resolveNpcVoiceType(guid);
+            audioCoordinator_->getNpcVoiceManager()->playGreeting(guid, voiceType, renderPos);
+        }
+    });
+
+    // NPC farewell callback - play farewell voice line
+    gameHandler_.setNpcFarewellCallback([this](uint64_t guid, const glm::vec3& position) {
+        if (audioCoordinator_ && audioCoordinator_->getNpcVoiceManager()) {
+            glm::vec3 renderPos = core::coords::canonicalToRender(position);
+            audio::VoiceType voiceType = resolveNpcVoiceType(guid);
+            audioCoordinator_->getNpcVoiceManager()->playFarewell(guid, voiceType, renderPos);
+        }
+    });
+
+    // NPC vendor callback - play vendor voice line
+    gameHandler_.setNpcVendorCallback([this](uint64_t guid, const glm::vec3& position) {
+        if (audioCoordinator_ && audioCoordinator_->getNpcVoiceManager()) {
+            glm::vec3 renderPos = core::coords::canonicalToRender(position);
+            audio::VoiceType voiceType = resolveNpcVoiceType(guid);
+            audioCoordinator_->getNpcVoiceManager()->playVendor(guid, voiceType, renderPos);
+        }
+    });
+
+    // NPC aggro callback - play combat start voice line
+    gameHandler_.setNpcAggroCallback([this](uint64_t guid, const glm::vec3& position) {
+        if (audioCoordinator_ && audioCoordinator_->getNpcVoiceManager()) {
+            glm::vec3 renderPos = core::coords::canonicalToRender(position);
+            audio::VoiceType voiceType = resolveNpcVoiceType(guid);
+            audioCoordinator_->getNpcVoiceManager()->playAggro(guid, voiceType, renderPos);
+        }
+    });
+}
+
+}} // namespace wowee::core