The standalone CLI is now a named, per-platform download:

    singalong-cli-linux-amd64        statically linked, no dependencies
    singalong-cli-macos-arm64        system frameworks only
    singalong-cli-windows-amd64.exe  static CRT

That is what an agent or a script should download — one file, chmod +x, run.
The release page leads with the table so the choice needs no guessing, and says
not to reach for the .deb/.rpm/.AppImage/.dmg/.exe instead: those are the desktop
player, which needs a webview to run.

Installing the player still gets you both halves: `sing-along fetch ~/Music`
works from the same binary that opens the window.

Also fixes the Linux CI build, which failed to find `x86_64-linux-musl-gcc`
(ring compiles C and needs a musl-targeted compiler — `musl-tools` provides it).