Restore runtime state on startup (#23326)

* add class

* restore runtime state in dispatcher

* restore on startup with special case for profile

* add tests

* update docs

* mypy

frigate/api/app.py

@@ -908,6 +908,11 @@ def config_set(request: Request, body: AppConfigSetBody):
                     status_code=500,
                 )
 
+            # drop runtime overrides for any fields the user just rewrote in
+            # yaml so a stale override doesn't silently win after restart
+            if request.app.dispatcher is not None:
+                request.app.dispatcher.clear_runtime_state_for_yaml_keys(updates.keys())
+
             if body.requires_restart == 0 or body.update_topic:
                 old_config: FrigateConfig = request.app.frigate_config
                 request.app.frigate_config = config