feat: Update plugin manager integration with lucide-react icons and improve RoomInput component logic

docs/PLUGIN_API.md

@@ -105,6 +105,7 @@ interface PluginContext {
   pluginId: string;
   matrixClient: MatrixClient;
   React: typeof import('react');
+  lucide: typeof import('lucide-react');
   
   commands: CommandsAPI;
   messages: MessagesAPI;
@@ -416,6 +417,8 @@ interface UIButtonDefinition {
   location: UILocation;
   label: string;
   icon?: string;
+  /** Lucide icon name, e.g. `ImagePlay`. Also supported via `icon: 'lucide:ImagePlay'`. */
+  lucideIcon?: string;
   position?: UIButtonPosition;
   onClick?: () => void | Promise<void>;
 }