Add submission snapshots for grant-backed runs

[Aristide021]

This draft PR adds three submission-style record folders for current Parameter Golf work.

Included:

• records/track_non_record_16mb/2026-03-19_ValOnly_SlidingWindow_mlx/
• records/track_10min_16mb/2026-03-19_QAT_Int6_MLP3_SlidingWindow/
• records/track_10min_16mb/2026-03-21_SWA_BigramHash_SmearGate_Int5MLP_MuonWD/

Current evidence:

• The MLX non-record run includes a real train.log, artifact under 16MB, and end-to-end validation of training, quantization/export, and evaluation.
• The two track_10min_16mb folders are code snapshots prepared in record format, but they do not yet include H100 train.log files or final metrics.

Why draft:

• I am applying for challenge compute credits and need a reviewable PR link.
• Final 10-minute-track metrics and logs will be added after funded H100 runs.

Intent:

• Use the MLX run as pipeline validation evidence.
• Backfill the pending 10-minute submission folders with verified H100 logs and metrics once compute is available.