fix: pass commit short hash as version to UI sidebar

Add VITE_APP_VERSION build arg to UI Dockerfile, pass short SHA from
CI docker build step. vite.config.ts truncates to 7 chars so both
CI build and Docker build produce consistent short hashes.

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

ui/Dockerfile

@@ -14,7 +14,9 @@ RUN echo "//gitea.siegeln.net/api/packages/cameleer/npm/:_authToken=${REGISTRY_T
     rm -f .npmrc
 
 ARG VITE_ENV_NAME=PRODUCTION
+ARG VITE_APP_VERSION=dev
 ENV VITE_ENV_NAME=$VITE_ENV_NAME
+ENV VITE_APP_VERSION=$VITE_APP_VERSION
 RUN npm run build
 
 FROM nginx:1.27-alpine