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/V2GDecoderNet.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <AssemblyTitle>V2GDecoderNet</AssemblyTitle>
+    <AssemblyDescription>C# port of OpenV2G EXI codec for V2G protocol messages</AssemblyDescription>
+    <AssemblyConfiguration>Release</AssemblyConfiguration>
+    <AssemblyCompany>V2GDecoder Port</AssemblyCompany>
+    <AssemblyProduct>V2GDecoderNet</AssemblyProduct>
+    <Copyright>Copyright © 2024</Copyright>
+    <AssemblyVersion>1.0.0.0</AssemblyVersion>
+    <FileVersion>1.0.0.0</FileVersion>
+  </PropertyGroup>
+
+</Project>