Console errors on every page (provolta/messages 404)

Every page logs two red errors: GET /api/chat/provolta/messages?after=0&limit=1 returns 404. It looks broken in DevTools, costs a request on each page, and hides real errors.

Either mount the route (return {messages:[]}), or have ai.js check a feature flag first and stop polling after the first 404 (remember it in sessionStorage).