Add v7: legal score-first TTT eval (PR openai#461 recipe)

Our v1 base (1.1232 pre-TTT) + legal TTT should give ~1.1211.
PR openai#473 gets 1.1213 from a 1.1234 base — our base is 0.0002 better.

TTT recipe: 32K-token chunks, score-first (inference_mode), then
train (SGD lr=0.002, momentum=0.9, 3 epochs, freeze blocks 0-1,
cosine LR decay across chunks, grad clip 1.0).

Removed TTT burst (replaced by legal TTT eval).
1499 lines (under 1500 limit).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Octavian