fix: suspend gravity for 10s after world entry to prevent WMO fall-through

Stormwind WMO collision takes 25+ seconds to fully load. The warmup
ground check couldn't detect the WMO floor because collision data
wasn't finalized yet. Player spawned and immediately fell through
the unloaded WMO floor into the terrain below (Dun Morogh).

New approach: suspendGravityFor(10s) after world entry. Gravity is
disabled (Z position frozen) until either:
1. A floor is detected by the collision system (gravity resumes instantly)
2. The 10-second timer expires (gravity resumes as fallback)

This handles the case where WMO collision loads during the first few
seconds of gameplay — the player hovers at spawn Z until the floor
appears, then lands normally.

Also fixes faction language for chat (ORCISH for Horde, COMMON for
Alliance) and adds SMSG_MESSAGECHAT diagnostic logging.

include/rendering/camera_controller.hpp

@@ -126,6 +126,7 @@ public:
     void setFacingYaw(float yaw) { facingYaw = yaw; }  // For taxi/scripted movement
     void clearMovementInputs();
     void suppressMovementFor(float seconds) { movementSuppressTimer_ = seconds; }
+    void suspendGravityFor(float seconds) { gravitySuspendTimer_ = seconds; }
 
     // Auto-follow: walk toward a target position each frame (WoW /follow).
     // The caller updates *targetPos every frame with the followed entity's render position.
@@ -270,6 +271,8 @@ private:
 
     // Movement input suppression (after teleport/portal, ignore held keys)
     float movementSuppressTimer_ = 0.0f;
+    // Gravity suspension (after world entry, hold Z until ground detected)
+    float gravitySuspendTimer_ = 0.0f;
 
     // State
     bool enabled = true;