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"

src/rendering/terrain_manager.cpp

@@ -627,6 +627,14 @@ void TerrainManager::unloadTile(int x, int y) {
     }
 
     loadedTiles.erase(it);
+
+    // Clean up any models that are no longer referenced
+    if (m2Renderer) {
+        m2Renderer->cleanupUnusedModels();
+    }
+    if (wmoRenderer) {
+        wmoRenderer->cleanupUnusedModels();
+    }
 }
 
 void TerrainManager::unloadAll() {