refactor(connection): public protocol_active accessor replaces the remote entity's private reach-in; media_player module docstring describes the Phase 2 architecture (F7)

custom_components/nvidia_shield/connection.py

@@ -347,6 +347,15 @@ class ShieldConnectionManager:
         """Visible recent-task apps, ordered by recency."""
         return self.store.get(FIELD_RUNNING_APPS, [])
 
+    @property
+    def protocol_active(self) -> bool:
+        """True when the remote-protocol transport is wired for this entry.
+
+        Entities use this instead of reaching into ``_protocol``: a passive
+        manager means "no transport", not "broken transport".
+        """
+        return self._protocol is not None
+
     @property
     def is_on(self) -> bool | None:
         """Protocol power push (device reports on/off state)."""