Add WoW-style camera system with collision and first-person mode

- Implement orbit camera with smooth zoom and collision detection
- Add 50° slope limiting with sliding (prevents mountain climbing)
- Add first-person mode that hides player model and weapons
- Add floor clearance check to prevent camera clipping through ground
- Improve WMO wall collision with proper height range checks
- Add two-sided floor collision detection for WMO geometry
- Increase M2 render distance slightly for better visibility

src/rendering/m2_renderer.cpp

@@ -364,7 +364,7 @@ void M2Renderer::render(const Camera& camera, const glm::mat4& view, const glm::
     lastDrawCallCount = 0;
 
     // Distance-based culling threshold for M2 models
-    const float maxRenderDistance = 300.0f;  // Reduced for performance
+    const float maxRenderDistance = 400.0f;  // Balance between performance and visibility
     const float maxRenderDistanceSq = maxRenderDistance * maxRenderDistance;
     const glm::vec3 camPos = camera.getPosition();