Tray icon with live transfer progress and tabs menu

- AppTray: template menu-bar icon (22pt, adapts to light/dark). While
  transfers run it swaps to pre-rendered frames — faded arrows + a fill bar
  showing aggregate doneBytes/totalBytes of the queue (nearest 5%, throttled
  500ms); back to the glyph when idle. No runtime image encoding.
- Menu: one entry per tab (checkmark on the active one) with live per-tab
  transfer count and percentage (jobs mapped via session ids), an overall
  progress row while transferring, Show <app>, Quit. Selecting a tab
  activates the window and switches to it.
- First use of webview->bun messages: PanelsService pushes workspacesSync
  (tab names, sessions, active id) via a new ready-gated send proxy; verified
  end-to-end in the running app.
- engine.aggregateProgress(): totals + per-session breakdown over non-terminal
  jobs (unit-verified idle/mid-transfer/idle).

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

ui/src/app/panels.service.ts

@@ -1,4 +1,4 @@
-import { Injectable, computed, signal, type WritableSignal } from '@angular/core';
+import { Injectable, computed, effect, signal, type WritableSignal } from '@angular/core';
 import type { ConnectionConfig, FileEntry, SavedConnection } from '@shared/types';
 import { RpcService } from './rpc.service';
 import { ToastService } from './toast.service';
@@ -180,6 +180,21 @@ export class PanelsService {
   ) {
     this.newWorkspace();
 
+    // keep the bun-side tray informed about tabs (names, sessions, active)
+    if (this.rpc.available) {
+      effect(() => {
+        this.rpc.send.workspacesSync({
+          workspaces: this.workspaces().map((ws) => ({
+            id: ws.id,
+            name: this.workspaceName(ws),
+            remote: this.workspaceIsRemote(ws),
+            sessionIds: [ws.left.sessionId(), ws.right.sessionId()],
+          })),
+          activeId: this.activeWorkspaceId(),
+        });
+      });
+    }
+
     // a session died on its own — reset every panel bound to it, in any tab
     this.rpc.onSessionClosed((event) => {
       for (const workspace of this.workspaces()) {