Add consistent OCI labels to all container Dockerfiles

Every container now carries title, description, version, source, and
vendor labels per the OCI image spec. Version is derived from the
existing CONTAINER_APP_VERSION ARG at build time.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

containers/cv/Dockerfile

@@ -10,6 +10,13 @@ ARG CONTAINER_APP_VERSION=1.0.3
 
 FROM nginx:alpine
 
+ARG CONTAINER_APP_VERSION
+LABEL org.opencontainers.image.title="CV"
+LABEL org.opencontainers.image.description="Static site server for CV/resume"
+LABEL org.opencontainers.image.version="${CONTAINER_APP_VERSION}"
+LABEL org.opencontainers.image.source="https://forge.eblu.me/eblume/blumeops"
+LABEL org.opencontainers.image.vendor="blumeops"
+
 # Install curl for downloading release assets
 RUN apk add --no-cache curl