Integrate a new testkit endpoint and update package.json scripts to enable automated testing via `pnpm test` and `pnpm test:prod`, including a new test case for request body size limits.
Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 418bf6f8-212b-4bb0-a7a5-8231a061da4e
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 60472e18-59b7-4877-a9a2-16381573ab68
Replit-Helium-Checkpoint-Created: true
