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

include/rendering/vk_context.hpp

@@ -73,6 +73,8 @@ public:
     bool isSwapchainDirty() const { return swapchainDirty; }
     void markSwapchainDirty() { swapchainDirty = true; }
 
+    bool isDeviceLost() const { return deviceLost_; }
+
     // MSAA
     VkSampleCountFlagBits getMsaaSamples() const { return msaaSamples_; }
     void setMsaaSamples(VkSampleCountFlagBits samples);
@@ -131,6 +133,7 @@ private:
     std::vector<VkImageView> swapchainImageViews;
     std::vector<VkFramebuffer> swapchainFramebuffers;
     bool swapchainDirty = false;
+    bool deviceLost_ = false;
 
     // Per-frame resources
     FrameData frames[MAX_FRAMES_IN_FLIGHT];