feat: add Jest testing framework and implement unit tests for configuration and service logic

jest.config.js

@@ -0,0 +1,21 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/src', '<rootDir>/tests'],
+  testMatch: [
+    '**/__tests__/**/*.ts',
+    '**/?(*.)+(spec|test).ts'
+  ],
+  transform: {
+    '^.+\\.ts$': 'ts-jest',
+  },
+  collectCoverageFrom: [
+    'src/**/*.ts',
+    '!src/**/*.d.ts',
+    '!src/index.ts'
+  ],
+  coverageDirectory: 'coverage',
+  coverageReporters: ['text', 'lcov', 'html'],
+  setupFilesAfterEnv: ['<rootDir>/tests/setup.ts'],
+  testTimeout: 10000
+};