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

package.json

@@ -7,7 +7,10 @@
     "build": "tsc",
     "start": "node dist/index.js",
     "dev": "ts-node src/index.ts",
-    "watch": "tsc --watch"
+    "watch": "tsc --watch",
+    "test": "jest",
+    "test:watch": "jest --watch",
+    "test:coverage": "jest --coverage"
   },
   "keywords": [
     "discord",
@@ -24,8 +27,11 @@
   },
   "devDependencies": {
     "@types/node": "^20.10.5",
+    "@types/jest": "^29.5.8",
     "typescript": "^5.3.3",
-    "ts-node": "^10.9.2"
+    "ts-node": "^10.9.2",
+    "jest": "^29.7.0",
+    "ts-jest": "^29.1.1"
   }
 }