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>

src/bun/rpc-handlers.ts

@@ -1,5 +1,5 @@
 import { BrowserView, Utils } from "electrobun/bun";
-import type { AppRPC } from "../shared/rpc";
+import type { AppRPC, WorkspaceSyncInfo } from "../shared/rpc";
 import { effectiveConcurrency, type Result } from "../shared/types";
 import { readFileText, writeFileText, type EditManager } from "./edits";
 import type { SessionRegistry } from "./fs/registry";
@@ -23,6 +23,7 @@ export interface AppDeps {
 	events: {
 		sessionClosed: (info: { sessionId: string; reason: string }) => void;
 		connectionsChanged: () => void;
+		workspacesSync: (sync: WorkspaceSyncInfo) => void;
 	};
 }
 
@@ -202,6 +203,9 @@ export function createAppRPC({ registry, engine, store, settings, edits, events
 						return {};
 					}),
 			},
+			messages: {
+				workspacesSync: (sync) => events.workspacesSync(sync),
+			},
 		},
 	});
 }