Add pkgs.uv to systemd.services.hermes-agent.path so that CronJobs
and terminal sessions can execute PEP 723 scripts via 'uv run'
(e.g. garmin-daily.py for Garmin Connect health data).
Also adds uv to environment.systemPackages for general availability.
- Fix hardcoded user path in webapps.nix (use homeDirectory)
- Normalize wallpapers option to use .enable suffix
- Remove duplicate FZF keybind declaration
- Update comments to match actual implementation
