chore(release): v1.21.3

Adds the Coach goal / if-then-plan memory model (propose-then-confirm,
encrypted, migration 0194) and a standing Coach quality harness (graded
golden set + red-team in CI, optional nightly model judge off by default).
Caches the dashboard snapshot per language. No breaking changes.

docs/api/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.21.2.1
+  version: 1.21.3
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.