fix(consent): a withdrawn AI consent stays withdrawn, and the web can withdraw

The settings mount fires an idempotent consent heal so an account that
predates the gate does not fall into the no-key state. It looked only for
an active receipt, so a deliberate withdrawal — which sets revokedAt —
read the same as never having consented, and the next visit to the AI
settings granted again, writing an audit row for an act the user never
performed. GDPR Art. 7 (3) puts withdrawal on the same footing as the
grant; one undone by a page load is not a withdrawal.

The mint now distinguishes the two callers. The mount heal grants only to
an account with no consent history at all and leaves a revocation
standing; switching document auto-read on is the consent act itself and
may supersede an earlier revocation. The revocation is re-checked inside
the transaction so a withdrawal landing mid-mint is not overwritten.

The revoke endpoint has existed since v1.4.40 but only the native client
called it: on the web, consent could be given and never taken back. The
AI settings now carry the standing decision and the control that changes
it, in all six languages.

docs/api/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.30.31
+  version: 1.30.32
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.