Add prettier

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -9,7 +9,9 @@
     "start": "node dist/index.js",
     "dev": "tsx src/index.ts",
     "auth": "tsx src/whatsapp-auth.ts",
-    "typecheck": "tsc --noEmit"
+    "typecheck": "tsc --noEmit",
+    "format": "prettier --write \"src/**/*.ts\"",
+    "format:check": "prettier --check \"src/**/*.ts\""
   },
   "dependencies": {
     "@whiskeysockets/baileys": "^7.0.0-rc.9",
@@ -24,6 +26,7 @@
     "@types/better-sqlite3": "^7.6.12",
     "@types/node": "^22.10.0",
     "@types/qrcode-terminal": "^0.12.2",
+    "prettier": "^3.8.1",
     "tsx": "^4.19.0",
     "typescript": "^5.7.0"
   },