Remove automatic push trigger on main/master branches and desktop-client path changes, keeping only manual workflow_dispatch. Remove self-hosted runner requirement to allow running on any Linux runner.
Add workflow to build Windows desktop client using cargo-xwin on Linux runners. Install Node.js 22, Rust with x86_64-pc-windows-msvc target, and required system dependencies including NSIS for installer creation. Build bundled Windows tunnel helper and desktop client installer, then upload both NSIS installer artifacts and raw executables.
