Add BOS-masked SmearGate record

[ZanePeycke]

Adds a clean 10min/16MB record candidate based on the PR #1787/#1797 CaseOps + SparseAttnGate + SmearGate + asymmetric LQER + phased score-before-update TTT lineage.

Key result:

• 3-seed mean: 1.06654079 BPB
• Sample std: 0.00122292 BPB
• Seeds: 42, 314, 1234
• Max artifact: 15,950,966 bytes
• Train time: 599.579s-599.652s
• TTT eval time: 272.1s-356.7s

Results:

Seed	Steps	Train shards	Pre-quant BPB	Quantized BPB	Post-TTT BPB	Artifact bytes	Train time	TTT eval time
42	5047	240	1.06944908	1.07891097	1.06642781	15,950,222	599.600s	356.7s
314	5036	240	1.06882706	1.07790190	1.06537828	15,950,966	599.579s	322.1s
1234	5026	240	1.07098567	1.08042471	1.06781627	15,950,455	599.652s	272.1s
Mean			1.06975394	1.07907919	1.06654079	15,950,548	599.610s	317.0s
Std			0.00111113	0.00126979	0.00122292	381	0.038s	42.5s

Compliance notes:

• Includes train_seed42.log, train_seed314.log, train_seed1234.log.
• Artifact stays under the decimal 16,000,000-byte cap.
• Training and evaluation stay under the 600s budgets on 8xH100 SXM.
• TTT remains score-before-update.
• CaseOps BPB uses the original UTF-8 byte sidecar.
• SmearGate is BOS-masked in both normal and TTT forward paths to prevent cross-document residual carry into a new document.

This is intended as a clean/reproducible submission candidate and explicitly addresses the document-boundary SmearGate issue discussed in the #1797 audit thread.