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/tray.ts

@@ -0,0 +1,130 @@
+import { Tray, type BrowserWindow } from "electrobun/bun";
+import { BRANDING } from "../shared/branding";
+import type { WorkspaceSyncInfo } from "../shared/rpc";
+import type { TransferEngine } from "./transfers/engine";
+
+const BASE_IMAGE = "views://assets/tray/tray-44-template.png";
+const PROGRESS_IMAGE = (pct: number) => `views://assets/tray/progress/p${pct}.png`;
+const REFRESH_THROTTLE_MS = 500;
+
+/**
+ * Menu-bar icon: the app glyph when idle; while transfers run the icon swaps
+ * to pre-rendered frames (faded arrows + fill bar = queue doneBytes/totalBytes).
+ * The menu lists the tabs (synced from the webview) with per-tab job info.
+ */
+export class AppTray {
+	private tray: Tray;
+	private tabs: WorkspaceSyncInfo = { workspaces: [], activeId: 0 };
+	private lastRefresh = 0;
+	private refreshTimer: ReturnType<typeof setTimeout> | null = null;
+	private currentImage = BASE_IMAGE;
+	/** Forwards tray menu actions the UI must handle (activate-tab:<id>). */
+	onAction: (action: string) => void = () => {};
+
+	constructor(
+		private win: BrowserWindow,
+		private engine: TransferEngine,
+	) {
+		this.tray = new Tray({
+			title: "",
+			image: BASE_IMAGE,
+			template: true,
+			width: 22,
+			height: 22,
+		});
+
+		this.tray.on("tray-clicked", (event) => {
+			const { action } = (event as { data: { action: string } }).data;
+			if (!action) return; // icon click with a menu set -> macOS opens the menu
+			if (action === "show-app") {
+				this.win.activate();
+			} else if (action === "quit") {
+				process.exit(0); // electrobun's clean-quit override
+			} else if (action.startsWith("activate-tab:")) {
+				this.win.activate();
+				this.onAction(action);
+			}
+		});
+
+		this.rebuildMenu();
+	}
+
+	updateTabs(sync: WorkspaceSyncInfo): void {
+		this.tabs = sync;
+		this.scheduleRefresh();
+	}
+
+	/** Called on every engine update; throttled internally. */
+	updateProgress(): void {
+		this.scheduleRefresh();
+	}
+
+	private scheduleRefresh(): void {
+		const now = Date.now();
+		const wait = Math.max(0, REFRESH_THROTTLE_MS - (now - this.lastRefresh));
+		if (this.refreshTimer) return;
+		this.refreshTimer = setTimeout(() => {
+			this.refreshTimer = null;
+			this.lastRefresh = Date.now();
+			this.refresh();
+		}, wait);
+	}
+
+	private refresh(): void {
+		const progress = this.engine.aggregateProgress();
+
+		// icon: nearest 5% frame while transferring, base glyph when idle
+		let image = BASE_IMAGE;
+		if (progress.activeCount > 0 && progress.totalBytes > 0) {
+			const pct = Math.round(((progress.doneBytes / progress.totalBytes) * 100) / 5) * 5;
+			image = PROGRESS_IMAGE(Math.max(0, Math.min(100, pct)));
+		}
+		if (image !== this.currentImage) {
+			this.currentImage = image;
+			this.tray.setImage(image);
+		}
+
+		this.rebuildMenu(progress);
+	}
+
+	private rebuildMenu(progress = this.engine.aggregateProgress()): void {
+		const items: Parameters<Tray["setMenu"]>[0] = [];
+
+		for (const ws of this.tabs.workspaces) {
+			const jobs = ws.sessionIds
+				.map((id) => progress.bySession[id])
+				.filter((v): v is NonNullable<typeof v> => !!v);
+			const count = jobs.reduce((n, j) => n + j.count, 0);
+			const total = jobs.reduce((n, j) => n + j.total, 0);
+			const done = jobs.reduce((n, j) => n + j.done, 0);
+			const suffix = count
+				? ` — ${count} transfer${count === 1 ? "" : "s"} · ${total ? Math.round((done / total) * 100) : 0}%`
+				: "";
+			items.push({
+				type: "normal",
+				label: `${ws.name}${suffix}`,
+				action: `activate-tab:${ws.id}`,
+				checked: ws.id === this.tabs.activeId,
+			});
+		}
+
+		if (progress.activeCount > 0) {
+			items.push({ type: "divider" });
+			const pct = progress.totalBytes
+				? Math.round((progress.doneBytes / progress.totalBytes) * 100)
+				: 0;
+			items.push({
+				type: "normal",
+				label: `${progress.activeCount} active transfer${progress.activeCount === 1 ? "" : "s"} · ${pct}%`,
+				action: "noop",
+				enabled: false,
+			});
+		}
+
+		items.push({ type: "divider" });
+		items.push({ type: "normal", label: `Show ${BRANDING.appName}`, action: "show-app" });
+		items.push({ type: "normal", label: "Quit", action: "quit" });
+
+		this.tray.setMenu(items);
+	}
+}