ci: release workflow to build and publish platform binaries

[vyshnavsdeepak]

Add a GitHub Actions workflow that builds platform binaries on tag push and uploads them as release assets. Required for the binary download path in ccswitch update to work.\n\nTargets:\n- ccswitch-aarch64-apple-darwin.tar.gz\n- ccswitch-x86_64-apple-darwin.tar.gz\n- ccswitch-x86_64-unknown-linux-gnu.tar.gz