chore(test): add test infrastructure, CI config, and security scanning

- Add Jenkinsfile with E2E/visual regression/security scan stages
- Add Stryker mutation testing configuration
- Add security header scanning script (check-security-headers.ts)
- Remove old playwright.config.ts (migrated to e2e/playwright.config.ts)
- Remove obsolete .claude/skills/impeccable
- Update jest config for test path patterns
- Update package.json with comprehensive test scripts
- Update .gitignore for stryker-tmp/ and .pi/ temp files

config/test/jest.config.js

@@ -1,6 +1,9 @@
+const path = require('path');
+
 module.exports = {
   preset: 'ts-jest',
   testEnvironment: 'jsdom',
+  rootDir: path.resolve(__dirname, '../..'),
   roots: ['<rootDir>/src'],
   testMatch: ['**/__tests__/**/*.test.{ts,tsx}', '**/*.test.{ts,tsx}'],
   // 仅收集实际可单元测试的目录的覆盖率，排除 pages/API routes/admin 等需集成/E2E 测试的代码