teachers-arabic-v1 — the ablation teachers + provenance labels

The four ByT5-base teachers behind the controlled auxiliary-supervision ablation (r5 none / r6 morph / r7 morph+news / r8 IPA) and the two sha256-provenance teacher-label files. Paper A's every number re-derivable: evaluate any checkpoint under the windowed protocol and score with interscript-sadeed-eval (PyPI). Parts reassemble by concatenation; digests in teachers-sha256.txt.