Fix WMO wall collision, normal mapping, POM backfill, and M2/WMO rendering performance

- Fix MOPY flag check (0x08 not 0x01) for proper wall collision detection
- Cap MAX_PUSH to PLAYER_RADIUS to prevent gradual clip-through
- Fix WMO doodad quaternion component ordering (X/Y swap)
- Linear normal map strength blend in shader for smooth slider control
- Enable shadow sampling for interior WMO groups (covered outdoor areas)
- Backfill deferred normal/height maps after streaming with descriptor rebind
- M2: prepareRender only iterates animated instances, bone dirty flag
- M2: remove worker thread VMA allocation, skip unready bone instances
- WMO: persistent visibility vectors, sequential culling
- Add FSR EASU/RCAS shaders

include/rendering/vk_context.hpp

@@ -84,6 +84,10 @@ public:
     bool isSwapchainDirty() const { return swapchainDirty; }
     void markSwapchainDirty() { swapchainDirty = true; }
 
+    // VSync (present mode)
+    bool isVsyncEnabled() const { return vsync_; }
+    void setVsync(bool enabled) { vsync_ = enabled; }
+
     bool isDeviceLost() const { return deviceLost_; }
 
     // MSAA
@@ -145,6 +149,7 @@ private:
     std::vector<VkFramebuffer> swapchainFramebuffers;
     bool swapchainDirty = false;
     bool deviceLost_ = false;
+    bool vsync_ = true;
 
     // Per-frame resources
     FrameData frames[MAX_FRAMES_IN_FLIGHT];