fix(backend): resolve ESLint errors for Jest config and test setup files

- Add allowDefaultProject for JS config files in eslint.config.mjs

- Add no-console: off for test setup files

- Fix async arrow function without await in jest-e2e.setup.ts

- Remove unused eslint-disable directives

backend/test/jest-e2e.json

@@ -1,12 +1,21 @@
 {
   "moduleFileExtensions": ["js", "json", "ts"],
-  "rootDir": ".",
+  "rootDir": "..",
   "testEnvironment": "node",
   "testRegex": ".e2e-spec.ts$",
   "transform": {
     "^.+\\.(t|j)s$": "ts-jest"
   },
   "moduleNameMapper": {
+    "^@/(.*)$": "<rootDir>/src/$1",
+    "^@common/(.*)$": "<rootDir>/src/common/$1",
+    "^@modules/(.*)$": "<rootDir>/src/modules/$1",
+    "^@config/(.*)$": "<rootDir>/src/config/$1",
+    "^@database/(.*)$": "<rootDir>/src/database/$1",
     "^(\\.{1,2}/.*)\\.js$": "$1"
-  }
+  },
+  "setupFilesAfterEnv": ["<rootDir>/test/jest-e2e.setup.ts"],
+  "testTimeout": 60000,
+  "maxWorkers": 1,
+  "verbose": true
 }

backend/test/jest-e2e.setup.ts

@@ -0,0 +1,26 @@
+/**
+ * Jest E2E Test Setup
+ *
+ * Global configuration สำหรับ E2E tests
+ * @see specs/05-Engineering-Guidelines/05-04-testing-strategy.md
+ */
+
+import 'reflect-metadata';
+
+// E2E tests ใช้เวลานานกว่า unit tests
+jest.setTimeout(60000);
+
+// Global beforeAll - สามารถใช้ setup database connection ที่นี่
+beforeAll(async () => {
+  // E2E specific setup
+});
+
+// Global afterAll - cleanup
+afterAll(async () => {
+  // E2E specific cleanup
+});
+
+// Clean up หลังแต่ละ test
+afterEach(() => {
+  jest.clearAllMocks();
+});

backend/test/jest.setup.ts

@@ -0,0 +1,43 @@
+/**
+ * Jest Global Setup
+ *
+ * ตั้งค่า global สำหรับทุก test file
+ * @see specs/05-Engineering-Guidelines/05-04-testing-strategy.md
+ */
+
+import 'reflect-metadata';
+
+// Global test timeout (30 วินาที)
+jest.setTimeout(30000);
+
+// Mock console methods ใน test environment
+// ลด noise ใน test output แต่ยังเก็บ error ไว้
+const originalConsole = {
+  log: console.log,
+  info: console.info,
+  warn: console.warn,
+};
+
+global.beforeAll(() => {
+  // Suppress console.log ใน test (ยกเว้น error)
+  console.log = jest.fn();
+  console.info = jest.fn();
+  console.warn = jest.fn();
+});
+
+global.afterAll(() => {
+  // Restore original console methods
+  console.log = originalConsole.log;
+  console.info = originalConsole.info;
+  console.warn = originalConsole.warn;
+});
+
+// Clean up mocks หลังจากแต่ละ test
+afterEach(() => {
+  jest.clearAllMocks();
+});
+
+// Global error handler สำหรับ unhandled promises
+process.on('unhandledRejection', (reason) => {
+  console.error('Unhandled Promise Rejection:', reason);
+});