Fix Stockades crash: suppress area triggers on initial login, handle VK_ERROR_DEVICE_LOST

Root cause: LOGIN_VERIFY_WORLD path did not set areaTriggerCheckTimer_ or
areaTriggerSuppressFirst_, so the Stockades exit portal (AT 503) fired
immediately on login, teleporting the player back to Stormwind and crashing
the GPU during the unexpected map transition.

Fixes:
- Set 5s area trigger cooldown + suppress-first in handleLoginVerifyWorld
  (same as SMSG_NEW_WORLD handler already did for teleports)
- Add deviceLost_ flag to VkContext so beginFrame returns immediately once
  VK_ERROR_DEVICE_LOST is detected, preventing infinite retry loops
- Track device lost from both fence wait and queue submit paths

src/game/game_handler.cpp

@@ -3456,6 +3456,12 @@ void GameHandler::handleLoginVerifyWorld(network::Packet& packet) {
         mountCallback_(0);
     }
 
+    // Suppress area triggers on initial login — prevents exit portals from
+    // immediately firing when spawning inside a dungeon/instance.
+    activeAreaTriggers_.clear();
+    areaTriggerCheckTimer_ = -5.0f;
+    areaTriggerSuppressFirst_ = true;
+
     // Send CMSG_SET_ACTIVE_MOVER (required by some servers)
     if (playerGuid != 0 && socket) {
         auto activeMoverPacket = SetActiveMoverPacket::build(playerGuid);