feat(FN-2635): add optimistic agent state updates across dashboard

- Apply optimistic start/stop state transitions in AgentsView and AgentDetailView action handlers
- Add optimistic behavior to AgentListModal while preserving rollback on API failure
- Expand unit test coverage for optimistic transitions and failure recovery in all three agent views
- Update dashboard TUI test expectation to align with the new agent state update flow

packages/cli/src/commands/dashboard-tui/__tests__/app.test.tsx

@@ -154,7 +154,7 @@ afterEach(() => {
   vi.useRealTimers();
 });
 
-async function waitForFrameContains(lastFrame: () => string | undefined, text: string, timeoutMs = 1200) {
+async function waitForFrameContains(lastFrame: () => string | undefined, text: string, timeoutMs = 3000) {
   const start = Date.now();
   while (Date.now() - start < timeoutMs) {
     if ((lastFrame() ?? "").includes(text)) return;