k3s: weekly image-refresh timer (pull floating tags + prune); NFS client support

modules/k3s/k3s.nix

@@ -24,4 +24,27 @@
       "ro"
     ];
   };
+
+  # Weekly rolling refresh: restart all deployments so floating :latest images
+  # are re-pulled, then prune dangling images.
+  systemd.services.image-refresh = {
+    description = "Pull latest floating images by restarting all deployments, then prune";
+    path = [ "/run/current-system/sw/bin" ];
+    script = ''
+      /run/current-system/sw/bin/k3s kubectl rollout restart deployments -A
+      sleep 120
+      /run/current-system/sw/bin/k3s crictl rmi --prune || true
+    '';
+    serviceConfig.Type = "oneshot";
+  };
+
+  systemd.timers.image-refresh = {
+    description = "Weekly image refresh";
+    wantedBy = [ "timers.target" ];
+    timerConfig = {
+      OnCalendar = "Sun *-*-* 04:30:00";
+      Persistent = true;
+      RandomizedDelaySec = "10m";
+    };
+  };
 }