add podman

hosts/forgejo-runner/forgejo-runner.nix

@@ -49,4 +49,38 @@
       };
     };
   };
+
+  systemd = {
+    services."forgejo-runner-container-updater" = {
+      description = "Update forgejo runner container images";
+      after = [ "network-online.target" ];
+      wants = [ "network-online.target" ];
+      serviceConfig.Type = "oneshot";
+      script = ''
+        set -uo pipefail
+        failed=0
+        images=(
+          docker.io/library/debian:stable-slim
+          docker.io/library/alpine:latest
+          docker.io/moby/buildkit:latest
+        )
+        for image in "''${images[@]}"; do
+          echo "Pulling $image..."
+          if ! ${pkgs.podman}/bin/podman pull "$image"; then
+            echo "Failed to pull $image"
+            failed=1
+          fi
+        done
+        exit $failed
+      '';
+    };
+    timers."forgejo-runner-container-updater" = {
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnCalendar = "daily";
+        RandomizedDelaySec = "30m";
+        Persistent = true;
+      };
+    };
+  };
 }