refactor: 优化测试框架配置

- 删除冗余的config/test/jest.config.js
- 将jest.config.js从符号链接改为独立配置文件
- 提升测试覆盖率阈值:
  - branches: 41% -> 50%
  - functions: 47% -> 55%
  - lines: 52% -> 60%
  - statements: 51% -> 60%
- 添加Jest缓存目录配置优化CI性能

jest.config.js

@@ -1 +0,0 @@
-config/test/jest.config.js

jest.config.js

@@ -0,0 +1,42 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'jsdom',
+  roots: ['<rootDir>/src'],
+  testMatch: ['**/__tests__/**/*.test.{ts,tsx}', '**/*.test.{ts,tsx}'],
+  collectCoverageFrom: [
+    'src/**/*.{ts,tsx}',
+    '!src/**/*.d.ts',
+    '!src/**/*.stories.{ts,tsx}',
+    '!src/**/__tests__/**',
+  ],
+  coverageThreshold: {
+    global: {
+      branches: 50,
+      functions: 55,
+      lines: 60,
+      statements: 60,
+    },
+  },
+  coverageReporters: ['text', 'lcov', 'html', 'json'],
+  coverageDirectory: 'coverage',
+  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx', 'json', 'node'],
+  moduleNameMapper: {
+    '^@/(.*)$': '<rootDir>/src/$1',
+  },
+  transform: {
+    '^.+\\.(ts|tsx)$': [
+      'ts-jest',
+      {
+        tsconfig: 'tsconfig.test.json',
+      },
+    ],
+  },
+  transformIgnorePatterns: [
+    'node_modules/(?!(nanoid|next-auth|@auth)/)',
+  ],
+  setupFilesAfterEnv: ['<rootDir>/jest.setup.js'],
+  testTimeout: 10000,
+  verbose: true,
+  maxWorkers: '50%',
+  cacheDirectory: '/tmp/jest-cache',
+};