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

e2e/package.json

@@ -3,10 +3,10 @@
   "version": "1.0.0",
   "private": true,
   "scripts": {
-    "test": "playwright test",
-    "test:standard": "TEST_TIER=standard playwright test --config=playwright.config.tiered.ts",
-    "test:fast": "TEST_TIER=fast playwright test --config=playwright.config.tiered.ts",
-    "test:deep": "TEST_TIER=deep playwright test --config=playwright.config.tiered.ts"
+    "test": "playwright test --config=../playwright.config.ts",
+    "test:fast": "TEST_TIER=fast playwright test --config=../playwright.config.ts",
+    "test:standard": "TEST_TIER=standard playwright test --config=../playwright.config.ts",
+    "test:deep": "TEST_TIER=deep playwright test --config=../playwright.config.ts"
   },
   "devDependencies": {
     "@playwright/test": "^1.48.0",