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>

C++/build.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+echo "Building V2GDecoder..."
+
+gcc -o V2GDecoder V2GDecoder.c \
+    src/iso1/*.c \
+    src/iso2/*.c \
+    src/din/*.c \
+    src/codec/*.c \
+    -I./src/codec \
+    -I./src/iso1 \
+    -I./src/iso2 \
+    -I./src/din \
+    -Wall -O2
+
+if [ $? -eq 0 ]; then
+    echo "Build successful! V2GDecoder created."
+    echo
+    echo "Usage:"
+    echo "  ./V2GDecoder ../Sample/test5.exi"
+else
+    echo "Build failed with error code $?"
+    exit 1
+fi