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

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@siwats/mxrelay-consumer",
-  "version": "1.2.2",
+  "version": "1.2.5",
   "description": "An internal TypeScript client library for transporting SMTP messages",
   "main": "lib/index.js",
   "module": "lib/index.esm.js",
@@ -9,7 +9,8 @@
     "lib/**/*",
     "src/**/*",
     "README.md",
-    "LICENSE"
+    "LICENSE",
+    "tsconfig*.json"
   ],
   "exports": {
     ".": {
@@ -24,14 +25,17 @@
     }
   },
   "scripts": {
-    "postinstall": "npm run build",
-    "build": "bun run build:cjs && bun run build:esm && bun run build:types",
+    "build": "npm run build:cjs && npm run build:esm && npm run build:types",
     "build:cjs": "tsc -p tsconfig.cjs.json",
     "build:esm": "tsc -p tsconfig.esm.json && cp lib-esm/index.js lib/index.esm.js && cp lib-esm/types.js lib/types.esm.js",
     "build:types": "tsc -p tsconfig.types.json",
     "clean": "rimraf lib lib-esm",
     "prepublishOnly": "npm run clean && npm run build",
+    "test": "jest",
+    "test:watch": "jest --watch",
+    "test:coverage": "jest --coverage",
     "lint": "eslint src/**/*.ts && tsc --noEmit",
+    "lint:fix": "eslint src/**/*.ts --fix",
     "lint:tsc": "tsc --noEmit",
     "lint:eslint": "eslint src/**/*.ts",
     "lint:eslint:fix": "eslint src/**/*.ts --fix",
@@ -87,8 +91,11 @@
     "eslint": "^8.49.0",
     "eslint-config-prettier": "^9.0.0",
     "eslint-plugin-prettier": "^5.0.0",
+    "jest": "^29.7.0",
     "prettier": "^3.0.3",
     "rimraf": "^5.0.1",
+    "ts-jest": "^29.1.1",
+    "ts-node": "^10.9.1",
     "typedoc": "^0.25.1",
     "typescript": "^5.2.2"
   },