Add spellbook, fix WMO floor clipping, and polish UI/visuals

- Add spellbook screen (P key) with Spell.dbc name lookup and action bar assignment
- Default Attack and Hearthstone spells available in single player
- Fix WMO floor clipping (gryphon roost) by tightening ceiling rejection threshold
- Darken ocean water, increase wave motion and opacity
- Add M2 model distance fade-in to prevent pop-in
- Reposition chat window, add slash/enter key focus
- Remove debug key commands (keep only F1 perf HUD, N minimap)
- Performance: return chat history by const ref, use deque for O(1) pop_front

include/rendering/m2_renderer.hpp

@@ -48,6 +48,7 @@ struct M2ModelGPU {
     bool collisionSmallSolidProp = false;
     bool collisionNarrowVerticalProp = false;
     bool collisionNoBlock = false;
+    bool collisionStatue = false;
 
     std::string name;