feat: add local pomodoro focus timer

Frontend-only 25m focus / 5m break timer with pause-resume-reset, deadline-based absolute timing, versioned localStorage persistence, cross-tab conflict protection, midnight-completion attribution, accessible stage controls, and reduced-motion support. Adds 专注 entry to desktop sidebar; mobile bottom nav unchanged; no notifications, task association, history, or cross-device sync. Also fixes mobile E2E task isolation and the stale calendar 390px overflow assertion.

frontend/e2e/task-pagination-position.spec.ts

@@ -14,26 +14,34 @@ async function createTask(request: APIRequestContext, baseURL: string, listId: s
   expect(response.ok(), await response.text()).toBeTruthy()
 }
 
-async function openInbox(page: Page) {
-  const inbox = page.locator('.sidebar').getByRole('button', { name: '收集箱', exact: true })
+async function createList(request: APIRequestContext, baseURL: string, name: string) {
+  const response = await request.post('/api/v1/lists', {
+    data: { name },
+    headers: { 'x-csrf-token': await csrf(request), origin: baseURL },
+  })
+  expect(response.ok(), await response.text()).toBeTruthy()
+  return response.json() as Promise<{ id: string }>
+}
+
+async function openList(page: Page, name: string) {
+  const list = page.locator('.sidebar').getByRole('button', { name, exact: true })
   if (await page.evaluate(() => window.innerWidth <= 930)) {
     await page.locator('main .topbar > button').first().click()
   }
-  await inbox.click()
+  await list.click()
 }
 
 test('task pagination stays below the list and returns to the list start after navigation', async ({ page, request, baseURL }) => {
-  const bootstrapResponse = await request.get('/api/v1/bootstrap')
-  expect(bootstrapResponse.ok()).toBeTruthy()
-  const inbox = (await bootstrapResponse.json()).lists.find((item: { is_inbox: boolean }) => item.is_inbox)
-  expect(inbox).toBeTruthy()
+  const nonce = crypto.randomUUID()
+  const listName = `分页验收清单 ${nonce}`
+  const list = await createList(request, baseURL!, listName)
 
   for (let index = 1; index <= 51; index += 1) {
-    await createTask(request, baseURL!, inbox.id, `分页验收任务 ${String(index).padStart(2, '0')}`)
+    await createTask(request, baseURL!, list.id, `分页验收任务 ${nonce} ${String(index).padStart(2, '0')}`)
   }
 
   await page.goto('/')
-  await openInbox(page)
+  await openList(page, listName)
 
   const taskList = page.locator('.task-list')
   const pager = page.locator('.pager')