chore(release): v1.38.11 — sign out everywhere means everywhere

Version anchors, the OpenAPI document, the changelog entry, and the
README sentence that still declared immunization records out of scope
while the vaccination record has shipped since v1.37.3.

docs/api/openapi.yaml

@@ -1,7 +1,7 @@
 openapi: 3.1.0
 info:
   title: HealthLog API
-  version: 1.38.10
+  version: 1.38.11
   description: >-
     Self-hosted personal-health-tracking PWA — public API surface for the iOS native client and external ingest.