When no custom directory is set, recordings go to an "SRF Recordings" folder
in the chosen library, or the first TV Shows library, so they show up without
adding a library by hand. The settings page gets a library picker, a check
that the directory is writable, and help for sandboxed systemd services.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
