Performance optimizations and collision improvements

Performance:
- Remove expensive inverse() from all vertex shaders (terrain, WMO, M2, water, character)
- Add uniform location caching to avoid repeated glGetUniformLocation calls
- Add proper frustum culling for WMO groups using AABB intersection
- Add distance-based culling for WMO and M2 instances
- Add cleanup of unused M2/WMO models when tiles unload

Collision & Movement:
- Add M2 doodad collision detection (fences, boxes, etc.)
- Reduce character eye height (5.0 -> 1.8) and collision radius (2.5 -> 0.5)
- Enable WoW-style movement speed by default (14 units/sec run, 5 walk, 9 back)
- Fix emote grammar ("You waves." -> "You wave.")

Misc:
- Rename window title to "Wowee"

include/rendering/wmo_renderer.hpp

@@ -102,6 +102,12 @@ public:
      */
     uint32_t getInstanceCount() const { return instances.size(); }
 
+    /**
+     * Remove models that have no instances referencing them
+     * Call periodically to free GPU memory
+     */
+    void cleanupUnusedModels();
+
     /**
      * Get total triangle count (all instances)
      */