优化页面交互并增强 Provider 配置能力

- 表单下拉框不再用 label 包裹，改为 div + aria-label，避免点击后
  下拉面板瞬间关闭
- Provider 卡片新增「从上游获取模型」和「修改」入口，支持编辑
  base URL、API Key 与 api_mode，凭据写入对应的环境变量
- 服务端抽出 provider-model-discovery 统一不同 api_mode 的模型发现，
  旧的 custom_providers 与新的 providers 字典结构都能正确更新
- Agent Bridge 改为后台启动，HTTP 接口在 Python 运行时就绪前即可用；
  worker 连接被拒时按类型重试，不重放可能已产生副作用的请求
- 断线重连后恢复 profiles、models 与会话列表，健康检查改为自调度
  的 setTimeout，离线时 2 秒后重试
- 批量删除确认文案改用 Popconfirm content，避免变成侧栏触发器文本

tests/e2e/form-dropdowns.spec.ts

@@ -0,0 +1,45 @@
+import { expect, test, type Locator, type Page } from '@playwright/test'
+import { authenticate, mockHermesApi, TEST_ACCESS_KEY } from './fixtures'
+
+async function openSelector(page: Page, select: Locator) {
+  await expect(select).not.toHaveClass(/arco-select-disabled/)
+  await select.click({ position: { x: 8, y: 16 } })
+  const popup = page.locator('.arco-select-dropdown:visible')
+  await expect(popup).toBeVisible()
+  // Wait past Arco's popup animation: label forwarding used to close the
+  // dropdown just after the initial visible assertion succeeded.
+  await page.waitForTimeout(300)
+  await expect(popup).toBeVisible()
+  return popup
+}
+
+test('auxiliary provider and model menus stay open and apply choices', async ({ page }) => {
+  await authenticate(page, TEST_ACCESS_KEY)
+  await mockHermesApi(page)
+  await page.goto('/#/hermes/models')
+  await page.getByRole('button', { name: 'Auxiliary Models', exact: true }).click()
+  await page.locator('.auxiliary-row').filter({ hasText: 'Vision' }).getByRole('button', { name: 'Edit', exact: true }).click()
+  const selects = page.locator('.auxiliary-form .arco-select')
+  await expect(selects).toHaveCount(2)
+  const providers = await openSelector(page, selects.nth(0))
+  await providers.locator('.arco-select-option', { hasText: 'Test Provider' }).click()
+  await expect(providers).toHaveCount(0)
+  await expect(selects.nth(0)).toContainText('Test Provider')
+  const models = await openSelector(page, selects.nth(1))
+  await models.locator('.arco-select-option', { hasText: 'test-model' }).click()
+  await expect(selects.nth(1)).toContainText('test-model')
+  await expect(page.locator('.auxiliary-form')).toBeVisible()
+})
+
+test('new workflow agent menu stays open and applies another profile', async ({ page }) => {
+  await authenticate(page, TEST_ACCESS_KEY, 'research')
+  await mockHermesApi(page)
+  await page.route(url => url.pathname.startsWith('/api/hermes/workflows'), route => route.fulfill({ json: { workflows: [] } }))
+  await page.goto('/#/hermes/workflow')
+  await page.getByRole('button', { name: 'New Workflow', exact: true }).click()
+  const select = page.locator('.workflow-create-form .arco-select')
+  const profiles = await openSelector(page, select)
+  await profiles.locator('.arco-select-option', { hasText: 'default' }).click()
+  await expect(select).toContainText('default')
+  await expect(page.locator('.workflow-create-form')).toBeVisible()
+})