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/bun/rpc-handlers.ts

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