server: dispatch python plugin events to systemManager listeners (#2086)

The python port of plugin-remote's notify() updates systemState but the
dispatch to systemManager.events was left as a commented-out TODO, so
systemManager.listen() callbacks never fire in python plugins/clients
(plugin-remote.ts dispatches via notifyEventDetails here). Port the
current typescript semantics: plain property changes update state and
notify listeners with the unwrapped value, everything else passes
through raw, and mixin property events no longer write device state.

Also fix EventRegistry.listenDevice to register callbacks in the
token-keyed listener set (it raised KeyError on the device id key,
diverging from event-registry.ts) so watch-mode device listeners work.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

server/python/plugin_remote.py

@@ -159,8 +159,8 @@ class EventRegistry(object):
             events = set()
             self.listeners[token] = events
         callback = ensure_not_coroutine(callback)
-        self.listeners[id].add(callback)
-        return EventListenerRegisterImpl(lambda: self.listeners[id].remove(callback))
+        events.add(callback)
+        return EventListenerRegisterImpl(lambda: events.discard(callback))
 
     def notify(
         self,
@@ -649,6 +649,7 @@ class PluginRemote:
     ):
         self.systemState: Mapping[str, Mapping[str, SystemDeviceState]] = {}
         self.nativeIds: Mapping[str, DeviceStorage] = {}
+        self.systemManager: SystemManager = None
         self.mediaManager: MediaManager
         self.clusterManager: ClusterManager
         self.consoles: Mapping[str, Future[Tuple[StreamReader, StreamWriter]]] = {}
@@ -1113,18 +1114,18 @@ class PluginRemote:
 
     async def notify(self, id, eventDetails: EventDetails, value):
         property = eventDetails.get("property")
-        if property:
-            state = None
-            if self.systemState:
-                state = self.systemState.get(id, None)
-                if not state:
-                    print("state not found for %s" % id)
-                    return
-                state[property] = value
-                # systemManager.events.notify(id, eventTime, eventInterface, property, value.value, changed);
-        else:
-            # systemManager.events.notify(id, eventTime, eventInterface, property, value, changed);
-            pass
+        if property and not eventDetails.get("mixinId"):
+            state = self.systemState.get(id, None) if self.systemState else None
+            if not state:
+                print("state not found for %s" % id)
+                return
+            state[property] = value
+            if self.systemManager:
+                self.systemManager.events.notifyEventDetails(
+                    id, eventDetails, value.get("value", None) if value else None
+                )
+        elif self.systemManager:
+            self.systemManager.events.notifyEventDetails(id, eventDetails, value)
 
     async def ioEvent(self, id, event, message=None):
         pass