Unify coordinate systems with canonical WoW world coordinates

Centralizes all coordinate conversions in core/coordinates.hpp with
proper canonical WoW coords (+X=North, +Y=West, +Z=Up). Fixes critical
tile calculation bug that was loading wrong surrounding tiles during
terrain streaming, and fixes position sync sending ADT-raw format
instead of canonical coordinates to the server.

include/rendering/camera_controller.hpp

@@ -31,6 +31,11 @@ public:
 
     void processMouseWheel(float delta);
     void setFollowTarget(glm::vec3* target);
+    void setDefaultSpawn(const glm::vec3& position, float yawDeg, float pitchDeg) {
+        defaultPosition = position;
+        defaultYaw = yawDeg;
+        defaultPitch = pitchDeg;
+    }
 
     void reset();