Update API endpoints for jobs and demo routes to enforce a maximum character limit of 500 for the 'request' field. Refine error messages to distinguish between missing input and input exceeding the character limit.
Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 418bf6f8-212b-4bb0-a7a5-8231a061da4e
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: 8c43b6a7-30d3-4806-8d46-3d364b17c284
Replit-Helium-Checkpoint-Created: true
f5811da508