Unified logging: Replace LogSystem with EditorConsoleSink

- Created EditorConsoleSink (implements ILogSink interface)
- EditorConsoleSink stores logs in memory buffer (max 1000 entries)
- Added to Debug::Logger in Application::Initialize()
- ConsolePanel now reads from EditorConsoleSink via static GetInstance()
- Removed separate LogSystem singleton
- Removed editor/src/Core/LogEntry.h (no longer needed)

Now Editor and Engine share the same Debug::Logger, with ConsolePanel
displaying logs via EditorConsoleSink.

engine/src/RHI/D3D12/D3D12CommandAllocator.cpp

@@ -1,5 +1,6 @@
 #include "XCEngine/RHI/D3D12/D3D12CommandAllocator.h"
 #include "XCEngine/RHI/D3D12/D3D12Enums.h"
+#include <stdio.h>
 
 namespace XCEngine {
 namespace RHI {
@@ -17,6 +18,11 @@ bool D3D12CommandAllocator::Initialize(ID3D12Device* device, CommandQueueType ty
     HRESULT hResult = device->CreateCommandAllocator(
         ToD3D12(type),
         IID_PPV_ARGS(&m_commandAllocator));
+    if (FAILED(hResult)) {
+        char buf[256];
+        sprintf(buf, "[D3D12CommandAllocator] CreateCommandAllocator failed: hr=0x%08X\n", hResult);
+        OutputDebugStringA(buf);
+    }
     return SUCCEEDED(hResult);
 }