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/rendering/renderer.cpp

@@ -946,6 +946,7 @@ void Renderer::applyMsaaChange() {
 
 void Renderer::beginFrame() {
     if (!vkCtx) return;
+    if (vkCtx->isDeviceLost()) return;
 
     // Apply deferred MSAA change between frames (before any rendering state is used)
     if (msaaChangePending_) {