macOS application menu

Standard menus (App: hide/quit; Edit: clipboard roles enabling Cmd+C/V/X/Z;
View: Refresh Cmd+R + fullscreen; Window: minimize/zoom/cycle) plus File with
New/Close Tab (Cmd+T/W), New Folder/File, and a Connect submenu built from
saved connections (folders as nested submenus, Connection Manager entry).
Custom actions forward to the webview as menuAction messages; the menu rebuilds
whenever connections change. macOS-only per electrobun support.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

ui/src/app/rpc.service.ts

@@ -18,6 +18,7 @@ export class RpcService {
   // (this froze the app), and signal coalescing would drop progress snapshots.
   private transferListeners = new Set<(s: TransferSnapshot) => void>();
   private closedListeners = new Set<(e: SessionClosedEvent) => void>();
+  private menuListeners = new Set<(action: string) => void>();
 
   private rpc: ReturnType<typeof Electroview.defineRPC<AppRPC>> | undefined;
   private ready: Promise<void> = Promise.resolve();
@@ -36,6 +37,9 @@ export class RpcService {
           sessionClosed: (event) => {
             for (const listener of this.closedListeners) listener(event);
           },
+          menuAction: ({ action }) => {
+            for (const listener of this.menuListeners) listener(action);
+          },
         },
       },
     });
@@ -60,6 +64,10 @@ export class RpcService {
     this.closedListeners.add(listener);
   }
 
+  onMenuAction(listener: (action: string) => void): void {
+    this.menuListeners.add(listener);
+  }
+
   /** Typed request proxy: `await rpc.request.listDir({...})`. Waits for the bridge. */
   get request() {
     const rpc = this.rpc;