fix: add uv to hermes-agent service PATH

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.

hosts/m3-hermes/services/hermes-agent.nix

@@ -70,6 +70,10 @@ in {
     '';
   };
 
+  # Ensure 'uv' is in the hermes-agent service PATH so CronJobs and terminal
+  # sessions can use 'uv run' for PEP 723 scripts (e.g. garmin-daily.py).
+  systemd.services.hermes-agent.path = [pkgs.uv];
+
   services.hermes-agent = {
     enable = true;
     addToSystemPackages = true;