Fix instance portals: WDT byte order, box trigger sizing, suppress ping-pong, WMO cache cleanup

- Fix WDT chunk magic constants to big-endian ASCII (matching ADTLoader)
- Add minimum effective size for box area triggers (90 units, like sphere 45-unit radius)
- Add areaTriggerSuppressFirst_ flag to prevent portal ping-pong on map transfer
- Add WMORenderer::clearAll() to clear models/textures on map change (prevents GPU crash)
- Increase WMO texture cache default to 8GB
- Fix setMapName called after loadTestTerrain so WMO renderer exists
- Save/restore player position around CMSG_AREATRIGGER to prevent bad DB persistence

include/game/game_handler.hpp

@@ -1500,6 +1500,7 @@ private:
     std::vector<AreaTriggerEntry> areaTriggers_;
     std::unordered_set<uint32_t> activeAreaTriggers_;  // triggers player is currently inside
     float areaTriggerCheckTimer_ = 0.0f;
+    bool areaTriggerSuppressFirst_ = false;  // suppress first check after map transfer
 
     float castTimeTotal = 0.0f;
     std::array<ActionBarSlot, 12> actionBar{};