perf: constexpr reciprocals, cache redundant lookups, consolidate texture maps

- Hoist DBC field index lookups before loops in game_handler (7 DBC iteration loops)
- Cache getSkybox()/getPosition() calls instead of redundant per-frame queries
- Merge textureHasAlphaByPtr_ + textureColorKeyBlackByPtr_ into single map
- Add constexpr for DEG_TO_RAD, reciprocal constants, physics delta
- Add reserve() for WMO/M2 collision grid queries and portal BFS
- Frustum plane normalize: inversesqrt instead of length+divide
- M2 particle emission: inversesqrt for direction normalization
- Parse creature display IDs from query response
- UI: show spell names/IDs as fallback instead of "Unknown"

src/rendering/camera_controller.cpp

@@ -18,6 +18,8 @@ namespace rendering {
 
 namespace {
 
+constexpr float kMaxPhysicsDelta = 1.0f / 30.0f;
+
 std::optional<float> selectReachableFloor(const std::optional<float>& terrainH,
                                           const std::optional<float>& wmoH,
                                           float refZ,
@@ -157,7 +159,7 @@ void CameraController::update(float deltaTime) {
         return;
     }
     // Keep physics integration stable during render hitches to avoid floor tunneling.
-    const float physicsDeltaTime = std::min(deltaTime, 1.0f / 30.0f);
+    const float physicsDeltaTime = std::min(deltaTime, kMaxPhysicsDelta);
 
     // During taxi flights, skip movement logic but keep camera orbit/zoom controls.
     if (externalFollow_) {