golden-v2 — plane-family parity corpus

golden-v2 — neural parity corpus additions

Adds the plane-family golden sets (Python-reference outputs):

• ara-diac-plane-1.0.jsonl — 50 rows, SadeedDiac-25 skeletons
• ara-diac-plane-large-1.0.jsonl — same inputs, large model

The quantized-tolerance contract

Int8 graphs are not byte-portable across onnxruntime builds: near-tied
logits flip argmax. Measured py-reference vs ruby (onnxruntime gem
0.11.6, arm64): 3/50 rows differ with 1-2 char diffs on 600-1000-char
rows. Cross-runtime parity for quantized models is therefore:
per-row char agreement >= 99.5%, corpus agreement >= 99.9%.
Deterministic graphs (maps, fp32 fixtures) remain byte-exact.