feat(FN-822): add visible stuck indicators on board and list with unified detection

- Unify stuck-task derivation using project settings (taskStuckTimeoutMs) instead of hardcoded values
- Thread taskStuckTimeoutMs through Board, Column, WorktreeGroup, and TaskCard components
- Add visual stuck indicator with pulsing animation on in-progress task cards
- Resolve merge conflicts with isSearchActive prop from main (both props coexist)
- Add taskStuck utility unit tests and update README with stuck indicator docs

packages/dashboard/app/utils/taskStuck.test.ts

@@ -0,0 +1,142 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
+import { isTaskStuck, countStuckTasks } from "./taskStuck";
+import type { Task } from "@fusion/core";
+
+const createTask = (overrides: Partial<Task> = {}): Task =>
+  ({
+    id: "FN-001",
+    description: "Test task",
+    column: "in-progress",
+    dependencies: [],
+    steps: [],
+    currentStep: 0,
+    log: [],
+    createdAt: "2026-01-01T00:00:00Z",
+    updatedAt: "2026-01-01T00:00:00Z",
+    columnMovedAt: "2026-01-01T00:00:00Z",
+    ...overrides,
+  }) as Task;
+
+describe("isTaskStuck", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2026-04-04T12:00:00Z"));
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("returns false when timeout is undefined (disabled)", () => {
+    const task = createTask({ updatedAt: "2026-04-04T06:00:00Z" });
+    expect(isTaskStuck(task, undefined)).toBe(false);
+  });
+
+  it("returns false when timeout is 0", () => {
+    const task = createTask({ updatedAt: "2026-04-04T06:00:00Z" });
+    expect(isTaskStuck(task, 0)).toBe(false);
+  });
+
+  it("returns false when timeout is negative", () => {
+    const task = createTask({ updatedAt: "2026-04-04T06:00:00Z" });
+    expect(isTaskStuck(task, -1)).toBe(false);
+  });
+
+  it("returns false for non-in-progress tasks", () => {
+    const task = createTask({ column: "todo", updatedAt: "2026-04-04T06:00:00Z" });
+    expect(isTaskStuck(task, 600000)).toBe(false);
+  });
+
+  it("returns false for recent in-progress tasks within timeout", () => {
+    const recent = new Date(Date.now() - 300000).toISOString(); // 5 minutes ago
+    const task = createTask({ updatedAt: recent });
+    expect(isTaskStuck(task, 600000)).toBe(false); // 10 minute timeout
+  });
+
+  it("returns true for stale in-progress tasks exceeding timeout", () => {
+    const stale = new Date(Date.now() - 600001).toISOString(); // just over 10 minutes
+    const task = createTask({ updatedAt: stale });
+    expect(isTaskStuck(task, 600000)).toBe(true);
+  });
+
+  it("returns false for malformed updatedAt", () => {
+    const task = createTask({ updatedAt: "not-a-date" });
+    expect(isTaskStuck(task, 600000)).toBe(false);
+  });
+
+  it("returns false for empty updatedAt", () => {
+    const task = createTask({ updatedAt: "" });
+    expect(isTaskStuck(task, 600000)).toBe(false);
+  });
+
+  it("handles tasks in triage column", () => {
+    const stale = new Date(Date.now() - 600001).toISOString();
+    const task = createTask({ column: "triage", updatedAt: stale });
+    expect(isTaskStuck(task, 600000)).toBe(false);
+  });
+
+  it("handles tasks in done column", () => {
+    const stale = new Date(Date.now() - 600001).toISOString();
+    const task = createTask({ column: "done", updatedAt: stale });
+    expect(isTaskStuck(task, 600000)).toBe(false);
+  });
+
+  it("returns true exactly at timeout boundary (greater than)", () => {
+    const boundary = new Date(Date.now() - 600001).toISOString();
+    const task = createTask({ updatedAt: boundary });
+    expect(isTaskStuck(task, 600000)).toBe(true);
+  });
+
+  it("returns false exactly at timeout boundary (equal)", () => {
+    const boundary = new Date(Date.now() - 600000).toISOString();
+    const task = createTask({ updatedAt: boundary });
+    expect(isTaskStuck(task, 600000)).toBe(false);
+  });
+});
+
+describe("countStuckTasks", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.setSystemTime(new Date("2026-04-04T12:00:00Z"));
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("returns 0 when timeout is undefined", () => {
+    const stale = new Date(Date.now() - 600001).toISOString();
+    const tasks = [createTask({ updatedAt: stale })];
+    expect(countStuckTasks(tasks, undefined)).toBe(0);
+  });
+
+  it("returns 0 when timeout is 0", () => {
+    const stale = new Date(Date.now() - 600001).toISOString();
+    const tasks = [createTask({ updatedAt: stale })];
+    expect(countStuckTasks(tasks, 0)).toBe(0);
+  });
+
+  it("counts only stuck tasks", () => {
+    const stale = new Date(Date.now() - 600001).toISOString();
+    const recent = new Date(Date.now() - 300000).toISOString();
+    const tasks = [
+      createTask({ id: "FN-001", updatedAt: stale }), // stuck
+      createTask({ id: "FN-002", updatedAt: recent }), // not stuck
+      createTask({ id: "FN-003", column: "todo", updatedAt: stale }), // not in-progress
+    ];
+    expect(countStuckTasks(tasks, 600000)).toBe(1);
+  });
+
+  it("returns 0 for empty task list", () => {
+    expect(countStuckTasks([], 600000)).toBe(0);
+  });
+
+  it("counts multiple stuck tasks", () => {
+    const stale = new Date(Date.now() - 600001).toISOString();
+    const tasks = [
+      createTask({ id: "FN-001", updatedAt: stale }),
+      createTask({ id: "FN-002", updatedAt: stale }),
+    ];
+    expect(countStuckTasks(tasks, 600000)).toBe(2);
+  });
+});