docs(xet): document v2 CAS API + batch reconstruction; fix xorb chunk limit - #2645

Bugbot Analysis Progress (1m 48s elapsed)

✅ Gathered PR context (4s)
✅ Completed bug detection (1m 44s)
✅ Posted analysis results (1s)

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

Request ID: serverGenReqId_1aef94ed-e7cb-4950-b3fa-e0bf9283317d