fix(e2e): 修复对话框关闭问题，完善 E2E 测试

- 修复 TDesign Dialog onConfirm 不自动关闭的问题
- 使用 useEffect 监听 mutation 状态自动关闭对话框
- 测试使用 waitForResponse 等待 API 响应
- 添加 clearDatabase 函数确保测试隔离
- 归档 e2e-real-backend 变更到 archive/2026-04-22
- 同步 e2e-testing spec 到主 specs

frontend/e2e/fixtures.ts

@@ -26,6 +26,18 @@ export interface SeedStatsInput {
   date: string
 }
 
+export async function clearDatabase(
+  request: import('@playwright/test').APIRequestContext,
+) {
+  const providers = await request.get(`${API_BASE}/api/providers`)
+  if (providers.ok()) {
+    const data = await providers.json()
+    for (const p of data) {
+      await request.delete(`${API_BASE}/api/providers/${p.id}`)
+    }
+  }
+}
+
 export async function seedProvider(
   request: import('@playwright/test').APIRequestContext,
   data: SeedProviderInput,
@@ -66,10 +78,15 @@ export async function seedModel(
 export async function seedUsageStats(statsData: SeedStatsInput[]) {
   const tempDir = process.env.NEX_E2E_TEMP_DIR
   if (!tempDir) {
-    throw new Error('NEX_E2E_TEMP_DIR not set')
+    throw new Error('NEX_E2E_TEMP_DIR not set - ensure playwright.config.ts is loaded')
   }
 
   const dbPath = path.join(tempDir, 'test.db')
+  
+  if (!fs.existsSync(dbPath)) {
+    throw new Error(`Database file not found at ${dbPath}. Backend may not have created it yet.`)
+  }
+  
   const SQL = await initSqlite()
   const buf = fs.readFileSync(dbPath)
   const db = new SQL.Database(buf)