feat: CI/CD workflow, Dockerfile, and K8s deployment

- Multi-stage Dockerfile (Maven + Node build, JRE runtime)
- Gitea Actions CI: build → docker → deploy
- K8s manifests: Deployment, Service (NodePort 30082), Ingress
- ServiceAccount + RBAC for kubectl access from pod
- Docker socket mount for image builds
- Ingress at deploy.cameleer.siegeln.net
- SPA config for serving frontend from Spring Boot
- cameleer-demo namespace for deployed apps

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

Dockerfile

@@ -0,0 +1,27 @@
+FROM --platform=$BUILDPLATFORM maven:3.9-eclipse-temurin-21 AS backend-build
+WORKDIR /build
+COPY pom.xml .
+RUN mvn dependency:go-offline -B || true
+COPY src/ src/
+RUN mvn clean package -DskipTests -B
+
+FROM --platform=$BUILDPLATFORM node:22-alpine AS ui-build
+WORKDIR /ui
+ARG REGISTRY_TOKEN
+COPY ui/package.json ui/package-lock.json ui/.npmrc ./
+RUN echo "//gitea.siegeln.net/api/packages/cameleer/npm/:_authToken=${REGISTRY_TOKEN}" >> .npmrc && \
+    npm ci
+COPY ui/ .
+RUN npm run build
+
+FROM eclipse-temurin:21-jre
+WORKDIR /app
+COPY --from=backend-build /build/target/cameleer-deploy-demo-*.jar /app/server.jar
+COPY --from=ui-build /ui/dist /app/static
+
+EXPOSE 8082
+ENV TZ=UTC
+ENTRYPOINT exec java -Duser.timezone=UTC \
+  -Dserver.port=8082 \
+  -Dspring.web.resources.static-locations=file:/app/static/ \
+  -jar /app/server.jar