Add .NET 8.0 C# port of OpenV2G EXI codec

- Port core EXI encoding/decoding functionality to C#
- Implement V2G protocol parsing and analysis
- Add simplified decoder/encoder for roundtrip testing
- Create comprehensive error handling with EXI exceptions
- Support both byte array and file stream operations
- Include packet structure analysis for V2GTP data
- Successfully builds and runs basic functionality tests

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

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

csharp/dotnet/obj/Debug/net6.0/V2GDecoderNet.genruntimeconfig.cache

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+73810ee1c6a0a650d2f788cf3e40cef8778b4cadbc6fd8cf871dac505c082c3e