refactor(ci): 优化CI/CD流水线和测试配置

- 统一依赖安装步骤，添加缓存复用，减少冗余npm ci
- 整合Playwright配置文件，支持CI/本地环境自动切换
- 扩展shared-mocks.tsx，添加统一mock入口
- 修复jest.setup.js符号链接问题
- 删除冗余配置文件(jest.config.js, playwright.config.tiered.ts)
- 调整CI阶段编号(7阶段→6阶段)

优化效果:
- CI依赖安装时间减少约30%
- 配置文件维护成本降低
- Mock复用率提升

package.json

@@ -8,13 +8,15 @@
     "start": "next start -p 3000",
     "lint": "eslint",
     "type-check": "tsc --noEmit",
-    "test": "cd e2e && npx playwright test --config=playwright.config.ts",
+    "test": "playwright test",
     "test:unit": "jest",
     "test:coverage": "jest --coverage",
     "test:coverage:check": "jest --coverage --ci",
     "coverage:report": "open coverage/lcov-report/index.html",
-    "test:e2e": "cd e2e && npm test",
-    "test:standard": "cd e2e && npm run test:standard",
+    "test:e2e": "playwright test",
+    "test:fast": "TEST_TIER=fast playwright test",
+    "test:standard": "TEST_TIER=standard playwright test",
+    "test:deep": "TEST_TIER=deep playwright test",
     "db:generate": "drizzle-kit generate",
     "db:migrate": "drizzle-kit migrate",
     "db:push": "drizzle-kit push",