fix: use standard dist/ output for Vite, copy to static/ explicitly

The relative outDir '../src/main/resources/static' resolved
unpredictably in Docker. Use standard 'dist/' output, then:
- Dockerfile: COPY --from=frontend /ui/dist/ to static/
- CI: cp -r dist/ to src/main/resources/static/

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

.gitea/workflows/ci.yml

@@ -33,6 +33,7 @@ jobs:
           echo "//gitea.siegeln.net/api/packages/cameleer/npm/:_authToken=${REGISTRY_TOKEN}" >> .npmrc
           npm ci
           npm run build
+          cp -r dist/ ../src/main/resources/static/
         env:
           REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}