Record Muon checkpoint 3126 durability

[qcznlp]

Summary

• record both corrected Muon runs reaching and remotely sealing checkpoint 3126
• refresh artifact-only progress from 26 to 28 of 60 resumable checkpoints
• refresh read-only W&B provenance at steps 3190 and 3140
• update the canonical handoff with exact Hugging Face commits and verified inventories

Both checkpoint receipts retain scientific_completion=false. This changes no training code, protocol, GPU job, or controller behavior.

Validation

• 15 focused progress, W&B, and incremental-backup tests
• four JSON artifacts parsed successfully
• portable paper evidence audit complete
• git diff check clean