chore(release): v1.32.18 — a dead Fitbit token no longer stamps a successful sync

Hold the Fitbit sync verdict when the token is dead or a write fails, and
verdict-gate the history backfill so a partial first-time import retries
instead of marking itself complete. No schema or contract change; the OpenAPI
version string tracks the bump.

docs/api/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.32.17
+  version: 1.32.18
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.