Simplify tray: static template icon, click focuses the app

The setImage-swapped progress frames lost the template treatment on macOS and
rendered black-on-dark once transfers started. Dial back per user decision:
the tray is now just the glyph (template image set once at construction, never
swapped) and clicking it activates the window — no menu, no progress effects.
Removes everything that only served the fancy version: progress frames +
generation, engine.aggregateProgress, the workspacesSync webview->bun channel
(schema, send proxy, panels effect, handlers) and the activate-tab action.

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

src/shared/rpc.ts

@@ -15,13 +15,7 @@ import type {
 // pulling in bun-only type modules.
 //
 // bun.requests    = calls the webview makes, handled in src/bun/rpc-handlers.ts
-// bun.messages    = fire-and-forget pushes from the webview (tray state)
 // webview.messages = push events from bun, handled in ui rpc.service.ts
-
-export interface WorkspaceSyncInfo {
-	workspaces: { id: number; name: string; remote: boolean; sessionIds: string[] }[];
-	activeId: number;
-}
 export type AppRPC = {
 	bun: {
 		requests: {
@@ -103,9 +97,7 @@ export type AppRPC = {
 			};
 			clearEditLeftovers: { params: Record<string, never>; response: Result };
 		};
-		messages: {
-			workspacesSync: WorkspaceSyncInfo;
-		};
+		messages: Record<never, never>;
 	};
 	webview: {
 		requests: Record<never, never>;