Add transport system, fix NPC spawning, and improve water rendering

Transport System (Phases 1-7):
- Implement TransportManager with Catmull-Rom spline path interpolation
- Add WMO dynamic transforms for moving transport instances
- Implement player attachment via world position composition
- Add test transport with circular path around Stormwind harbor
- Add /transport board and /transport leave console commands
- Reuse taxi flight spline system and external follow camera mode

NPC Spawn Fixes:
- Add smart ocean spawn filter: blocks land creatures at high altitude over water (Z>50)
- Allow legitimate water creatures at sea level (Z≤50) to spawn correctly
- Fixes Elder Grey Bears, Highland Striders, and Plainscreepers spawning over ocean
- Snap online creatures to terrain height when valid ground exists

NpcManager Removal:
- Remove deprecated NpcManager (offline mode no longer supported)
- Delete npc_manager.hpp and npc_manager.cpp
- Simplify NPC animation callbacks to use only creatureInstances_ map
- Move NPC callbacks to game initialization in application.cpp

Water Rendering:
- Fix tile seam gaps caused by per-vertex wave randomization
- Add distance-based blending: seamless waves up close (<150u), grid effect far away (>400u)
- Smooth transition between seamless and grid modes (150-400 unit range)
- Preserves aesthetic grid pattern at horizon while eliminating gaps when swimming

include/rendering/wmo_renderer.hpp

@@ -82,6 +82,13 @@ public:
      */
     void setInstancePosition(uint32_t instanceId, const glm::vec3& position);
 
+    /**
+     * Update the full transform of an existing instance (for moving transports)
+     * @param instanceId Instance to update
+     * @param transform World transform matrix
+     */
+    void setInstanceTransform(uint32_t instanceId, const glm::mat4& transform);
+
     /**
      * Remove WMO instance
      * @param instanceId Instance to remove