Merge story 74: agent lozenges float across UI during assignment

Resolves conflict in AgentPanel.test.tsx between story 73 (fade-out)
and story 74 (lozenge fly animation) - kept both the assertion and
the comment.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/components/AgentPanel.test.tsx

@@ -1,6 +1,14 @@
 import { act, render, screen, waitFor } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
-import { afterEach, beforeAll, beforeEach, describe, expect, it, vi } from "vitest";
+import {
+	afterEach,
+	beforeAll,
+	beforeEach,
+	describe,
+	expect,
+	it,
+	vi,
+} from "vitest";
 import type { AgentConfigInfo, AgentInfo } from "../api/agents";
 import { agentsApi } from "../api/agents";
 
@@ -337,15 +345,21 @@ describe("AgentPanel fade-out", () => {
 
 			const { container } = render(<AgentPanel />);
 
-			// Wait for the agent entry to appear
-			await waitFor(() => {
-				expect(
-					container.querySelector(
-						'[data-testid="agent-entry-73_remove_test:coder-1"]',
-					),
-				).toBeInTheDocument();
+			// With fake timers active, waitFor's polling setInterval never fires.
+			// Use act to flush pending promises and React state updates instead.
+			await act(async () => {
+				await Promise.resolve();
+				await Promise.resolve();
+				await Promise.resolve();
+				await Promise.resolve();
 			});
 
+			expect(
+				container.querySelector(
+					'[data-testid="agent-entry-73_remove_test:coder-1"]',
+				),
+			).toBeInTheDocument();
+
 			// Advance timers by 60 seconds and flush React state updates
 			await act(async () => {
 				vi.advanceTimersByTime(60_000);