ci: consolidate Nexus deployment and provenance

frontend/Dockerfile

@@ -7,6 +7,12 @@ COPY . .
 RUN pnpm build
 
 FROM nginx:1.27-alpine
+ARG NEXUS_VERSION=dev
+ARG NEXUS_GIT_SHA=unknown
+LABEL org.opencontainers.image.title="Nexus Web" \
+      org.opencontainers.image.source="https://git.noveria.net/bao/nexus" \
+      org.opencontainers.image.version="${NEXUS_VERSION}" \
+      org.opencontainers.image.revision="${NEXUS_GIT_SHA}"
 COPY nginx.conf /etc/nginx/conf.d/default.conf
 COPY --from=build /app/dist /usr/share/nginx/html
 EXPOSE 80