Backport Orca's d-bus remote fixes.

src/cthulhu/plugin_system_manager.py

@@ -669,14 +669,14 @@ class PluginSystemManager:
             logger.error(f"Failed to deregister D-Bus module for plugin {plugin_info.get_module_name()}: {error}")
 
     @dbus_service.command
-    def list_plugins(self):
+    def list_plugins(self) -> list[str]:
         """Returns a list of available plugin module names."""
         if not self._plugins:
             self.rescanPlugins()
         return [info.get_module_name() for info in self.plugins]
 
     @dbus_service.command
-    def list_active_plugins(self):
+    def list_active_plugins(self) -> list[str]:
         """Returns a list of currently active plugin module names."""
         return [info.get_module_name() for info in self.plugins if info.loaded]