Disable NV12 path for ANSCV by default. Currenly use cv::Mat** directly

include/GpuNV12SlotPool.h

@@ -97,7 +97,8 @@ struct GpuNV12Slot {
     // first — causing 1-2 second stalls.  Using a dedicated non-blocking
     // stream avoids this implicit sync entirely.
     // Stored as void* to avoid cuda_runtime.h in the header.
-    void* copyStream = nullptr;  // cudaStream_t
+    void* copyStream = nullptr;     // cudaStream_t
+
 };
 
 class GpuNV12SlotPool {
@@ -119,6 +120,7 @@ public:
     // Returns nullptr if pool full — caller falls back to CPU path.
     GpuNV12Slot* acquire(int gpuIdx, int w, int h);
 
+
     // Deferred release: moves slot from ACTIVE → COOLING.
     // Called from freeOwnedBuffers_locked() when GpuFrameData refcount → 0.
     // The slot becomes FREE after SLOT_COOLDOWN_MS elapses (checked in acquire).