remove: session operations center and progress panel

The bottom-right progress panel duplicated feedback already shown by
toasts. Remove it and the operation-tracking state to simplify the UI:

- Delete state/session-operations.tsx and session-progress-panel.tsx.
- Remove SessionOperationsProvider/SessionProgressPanel from AppShell.
- Remove startOperation/completeOperation calls from useInstanceActions
  and ToolStarter.
- Remove SessionOperationsProvider wrapper from DashboardPage.test.tsx.
- Remove .session-progress-panel CSS rules.
- Format use-events.test.ts mock to match project lint rules.

Quality gates: npm run typecheck, npm run lint, npm test -- --run
(87 passed).

apps/web/src/pages/DashboardPage.test.tsx

@@ -5,7 +5,6 @@ import { beforeEach, describe, expect, it, vi } from "vitest";
 
 import { HomePage } from "./DashboardPage";
 import { SessionsProvider } from "../state/sessions";
-import { SessionOperationsProvider } from "../state/session-operations";
 
 const mockDashboard = vi.fn();
 const mockSessions = vi.fn();
@@ -59,9 +58,7 @@ describe("HomePage", () => {
 		render(
 			<MemoryRouter>
 				<SessionsProvider>
-					<SessionOperationsProvider>
 						<HomePage />
-					</SessionOperationsProvider>
 				</SessionsProvider>
 			</MemoryRouter>,
 		);
@@ -81,9 +78,7 @@ describe("HomePage", () => {
 		render(
 			<MemoryRouter>
 				<SessionsProvider>
-					<SessionOperationsProvider>
 						<HomePage />
-					</SessionOperationsProvider>
 				</SessionsProvider>
 			</MemoryRouter>,
 		);