chore: set up MSW

This will help with mocking requests and responses from external services.

package.json

@@ -12,8 +12,10 @@
     "@cloudflare/workers-types": "^4.20240403.0",
     "@trivago/prettier-plugin-sort-imports": "^4.3.0",
     "@types/bun": "^1.1.2",
+    "msw": "^2.3.0",
     "prettier": "^3.2.5",
     "prettier-plugin-toml": "^2.0.1",
+    "typescript": "^5.4.5",
     "wrangler": "^3.47.0"
   }
 }