[idd] capture: copy software frames directly to IVSHMEM

Bypass cadence retention when the software render adapter is active.
Publish each available source frame immediately with one damage-aware
D3D copy into its final IVSHMEM resource.

Keep only one software copy in flight so newer frames are dropped
instead of queued behind stale work. Retain accumulated damage for the
next frame and skip static re-encodes when no image update is pending.

Use a row-major IVSHMEM texture when the shared heap supports it and
fall back to a direct IVSHMEM buffer copy otherwise. In indirect mode,
copy only damaged rows from readback memory into IVSHMEM.

idd/LGIdd/CD3D12Device.h

@@ -51,7 +51,8 @@ struct CD3D12Device
 
     CD3D12CommandQueue m_copyQueue;
     CD3D12CommandQueue m_computeQueue;
-    bool                m_computeEnabled = false;
+    bool                m_computeEnabled           = false;
+    bool                m_ivshmemTextureSupported  = false;
 
     bool HeapTest();
 
@@ -78,7 +79,9 @@ struct CD3D12Device
     ComPtr<ID3D12Device3> GetDevice() { return m_device; }
     ComPtr<ID3D12Heap   > GetHeap() { return m_ivshmemHeap; }
     bool IsIndirectCopy() { return m_indirectCopy; }
+    bool CanUseIVSHMEMTexture() { return m_ivshmemTextureSupported; }
 
+    CD3D12CommandSlot * GetCopySlot   ();
     CD3D12CommandSlot * GetCopySlot   (unsigned frameIndex);
     CD3D12CommandSlot * GetComputeSlot(unsigned frameIndex);
 };