Issue #67: re-run overfit-100 gate #523

Task

Re-run overfit-100 benchmark to verify overfit-100 gate.

Acceptance Criteria

• 500 steps training
• BPB < 0.5 on held-out set
• Run in experiments/overfit/overfit_100/

Dependencies

• Issue Phase 5: Native Sessions for tri-api + tri-bot #64: simple_backward fix
• Issue feat(spec): .tri Spec Linter — validate before pipeline #68: Trinity config

Refs

• EXP-001: Trinity physics

Commit

"exp(overfit): re-run overfit-100 gate"
Refs: #64, #68