chore: guard the v0 legacy bridge against non-renderer training clients - #1613

Bugbot Analysis Progress (43s elapsed)

✅ Gathered PR context (2s)
✅ Completed bug detection (40s)
✅ Posted analysis results (0s)

Final Result: Bugbot completed review - no issues found! ✅

Request ID: serverGenReqId_059897ae-dbe8-4a74-8a9b-3f9c81bcfb31