fix: 多选同步弹窗复用站点同步表单缓存

- 抽取站点地址与 Token 的 24 小时缓存工具
- 存储页与多选同步弹窗共用 pichost.site-sync-form
- 弹窗打开时读取最新缓存，修改后写回
- 增加缓存读取与过期测试

app/utils/site-sync-form.test.ts

@@ -0,0 +1,50 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import {
+  loadSiteSyncForm,
+  saveSiteSyncForm,
+  SITE_SYNC_FORM_STORAGE_KEY
+} from './site-sync-form'
+
+function createStorage(): Storage {
+  const values = new Map<string, string>()
+  return {
+    get length() {
+      return values.size
+    },
+    clear: () => values.clear(),
+    getItem: key => values.get(key) ?? null,
+    key: index => [...values.keys()][index] ?? null,
+    removeItem: key => values.delete(key),
+    setItem: (key, value) => values.set(key, value)
+  }
+}
+
+describe('site sync form cache', () => {
+  afterEach(() => {
+    vi.useRealTimers()
+    vi.unstubAllGlobals()
+  })
+
+  it('reads values saved by another component', () => {
+    vi.stubGlobal('localStorage', createStorage())
+    saveSiteSyncForm('http://127.0.0.1:3010', 'secret-token')
+
+    expect(loadSiteSyncForm()).toEqual({
+      targetBaseUrl: 'http://127.0.0.1:3010',
+      token: 'secret-token'
+    })
+  })
+
+  it('drops the cache after 24 hours', () => {
+    const storage = createStorage()
+    vi.stubGlobal('localStorage', storage)
+    vi.useFakeTimers()
+    vi.setSystemTime(new Date('2026-10-19T00:00:00Z'))
+    saveSiteSyncForm('http://target', 'token')
+
+    vi.setSystemTime(new Date('2026-10-20T00:00:01Z'))
+
+    expect(loadSiteSyncForm()).toBeNull()
+    expect(storage.getItem(SITE_SYNC_FORM_STORAGE_KEY)).toBeNull()
+  })
+})