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/water_renderer.cpp

@@ -44,7 +44,8 @@ bool WaterRenderer::initialize() {
             vec3 pos = aPos;
 
             FragPos = vec3(model * vec4(pos, 1.0));
-            Normal = mat3(transpose(inverse(model))) * aNormal;
+            // Use mat3(model) directly - avoids expensive inverse() per vertex
+            Normal = mat3(model) * aNormal;
             TexCoord = aTexCoord;
             WaveOffset = 0.0;