Floating monitor: magnet docking and admin memory actions

The magnet docks the monitor bottom-right: beside the minimap in the graph,
in the corner of the App view; dragging undocks it. Admins get Unload models
and Free models & cache. /free now needs admin.

tests/python/helpers.py

@@ -122,6 +122,7 @@ def comfy_routes(user_root, queue=None):
         table.route("*", prefix + "/prompt")(prompt)
         table.post(prefix + "/queue")(queue_route)
         table.post(prefix + "/interrupt")(ok)
+        table.post(prefix + "/free")(ok)
         table.route("*", prefix + "/manager/{tail:.*}")(ok)
         table.route("*", prefix + "/customnode/{tail:.*}")(ok)
     return table