feat: Add unit tests for backend validators and configure Jest.

Backend/jest.config.js

@@ -0,0 +1,22 @@
+/** @type {import('jest').Config} */
+const config = {
+    preset: 'ts-jest',
+    testEnvironment: 'node',
+    roots: ['<rootDir>/tests'],
+    testMatch: ['**/*.test.ts'],
+    moduleNameMapper: {
+        '^@/(.*)$': '<rootDir>/src/$1'
+    },
+    clearMocks: true,
+    collectCoverageFrom: [
+        'src/**/*.ts',
+        '!src/**/*.d.ts',
+        '!src/generated/**',
+        '!src/server.ts'
+    ],
+    transform: {
+        '^.+\\.tsx?$': ['ts-jest', { tsconfig: './tsconfig.test.json' }]
+    }
+};
+
+module.exports = config;