Seal CalVer synthetic data smoke

[DearKarl]

What changed

• implement the calendar-versioned deterministic synthetic table generator and entry point
• freeze the 2026.08.12.3 failure correction and 2026.08.12.4 minimum-column correction
• add schema, coverage, acceptance, replay, overlap, and hashing checks
• seal the passing 256-record data-smoke Evidence Card without committing payloads

Why

The first two non-overwriting smoke runs correctly hard-stopped on identity EDIT priors. The final correction makes paired Gold states edit-capable across the complete two-to-fourteen-column range and preserves both failed runs as evidence.

Validation

• 36 passed
• 256 requested / generated / accepted
• 64 records in each of Exact KEEP, Hard KEEP, Single Minimal Edit, and Complex Correction
• 64 complete same-role counterfactual pairs
• cross-role overlap audit PASS
• independent record, image, and SHA256SUMS verification PASS
• no model training, benchmark evaluation, or terminal input use