chore: update package version to 1.2.5 and add Jest testing framework

- Bump version in package.json and package-lock.json from 1.2.2 to 1.2.5
- Add Jest configuration file for testing
- Update build scripts to use npm instead of bun
- Add linting and testing scripts to package.json
- Include tsconfig files in package.json files array

jest.config.js

@@ -0,0 +1,20 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/src'],
+  testMatch: [
+    '**/__tests__/**/*.ts',
+    '**/?(*.)+(spec|test).ts'
+  ],
+  transform: {
+    '^.+\\.ts$': 'ts-jest',
+  },
+  collectCoverageFrom: [
+    'src/**/*.ts',
+    '!src/index.ts'
+  ],
+  coverageDirectory: 'coverage',
+  coverageReporters: ['text', 'lcov', 'html'],
+  testTimeout: 30000,
+  passWithNoTests: true
+};