feat: Complete cross-platform build system and folder reorganization

- Reorganize project structure: Port/ → DotNet/, VC/, C++/
- Add comprehensive cross-platform build automation
  - Windows: build_all.bat, build.bat files for all components
  - Linux/macOS: build_all.sh, build.sh files for all components
- Update all build scripts with correct folder paths
- Create test automation scripts (test_all.bat/sh)
- Update documentation to reflect new structure
- Maintain 100% roundtrip accuracy for test5.exi (pure EXI)
- Support both Windows MSBuild and Linux GCC compilation

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

DotNet/build.bat

@@ -0,0 +1,37 @@
+@echo off
+echo Building .NET V2GDecoder Project...
+
+rem .NET Core 빌드
+echo Building Debug configuration...
+dotnet build V2GDecoderNet.csproj -c Debug
+if %ERRORLEVEL% neq 0 (
+    echo ERROR: Debug 빌드 실패
+    pause
+    exit /b 1
+)
+
+echo Building Release configuration...  
+dotnet build V2GDecoderNet.csproj -c Release
+if %ERRORLEVEL% neq 0 (
+    echo ERROR: Release 빌드 실패
+    pause
+    exit /b 1
+)
+
+echo.
+echo ✅ .NET 빌드가 성공적으로 완료되었습니다
+echo.
+echo 생성된 파일들:
+if exist "bin\Debug\net8.0\V2GDecoderNet.exe" (
+    echo   📦 Debug: bin\Debug\net8.0\V2GDecoderNet.exe
+)
+if exist "bin\Release\net8.0\V2GDecoderNet.exe" (
+    echo   📦 Release: bin\Release\net8.0\V2GDecoderNet.exe
+)
+
+echo.
+echo 사용법:
+echo   dotnet run V2GDecoderNet.csproj ..\Sample\test5.exi
+echo   bin\Release\net8.0\V2GDecoderNet.exe ..\Sample\test5.exi
+
+pause