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>

Dockerfile

@@ -17,7 +17,7 @@ COPY mvnw pom.xml ./
 # Cache deps — only re-downloaded when POM changes
 RUN ./mvnw dependency:go-offline -B || true
 COPY src/ src/
-COPY --from=frontend /src/main/resources/static/ src/main/resources/static/
+COPY --from=frontend /ui/dist/ src/main/resources/static/
 RUN ./mvnw package -DskipTests -B
 
 # Runtime: target platform (amd64)