Adds the persistence layer for the AI consent audit trail required by
App-Store Guideline 5.1.2(i) and GDPR Art. 7:
- src/lib/validations/consent.ts — Zod schemas with a three-kind
discriminator (ai_full / ai_insights_only / ai_coach) and a 64 KB cap
on the opaque artefact so a misbehaving client can't fill the audit
table with multi-megabyte rows.
- src/lib/consent/receipts.ts — append-only helpers: createReceipt,
latestActiveReceipt, latestActiveReceiptsByKind, revokeLatest.
Revoke flips a single field on the existing row; a re-grant always
mints a fresh row, keeping the historical chain intact for legal
review.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
