Enable Windows x64 binary build for Opcode and update Tauri/Cargo config

[cto-new]

Summary

Enable Windows x64 binary build for Opcode by adding Windows targets and a reproducible build workflow.

Details

• Updated src-tauri/tauri.conf.json to include Windows targets (msi, nsis) and Windows bundle settings
• Updated src-tauri/Cargo.toml to add Windows dependencies (winapi, windows) for Windows target
• Added build-windows.sh to automate cross-compilation from Linux to Windows (Rust + MinGW-w64 + Bun, frontend build)
• Built Windows binaries: opcode.exe, opcode-web.exe, WebView2Loader.dll; created output directory windows-x64-binary with artifacts; added README
• Included a Windows build README and BUILD_SUMMARY documenting the build

Notes

• WebView2 Runtime is required on Windows

Warning: Task VM test is not passing, cto.new will perform much better if you fix the setup