fix: resolve critical deployment issues across Helm charts, Dockerfile, and K8s fallback

- Add helm/kubectl binaries and chart directory to backend Dockerfile
- Extend Helm templates for MongoDB/MariaDB database support (env vars, probes, ports)
- Add Redis and RabbitMQ Helm templates (deployment, service, secret, PVC)
- Add generic app-storage PVC and Fluent Bit sidecar with ES authentication
- Fix imagePullSecrets in K8s API fallback, prevent secret regeneration on redeploy
- Clean up Redis/RabbitMQ/FluentBit resources on app deletion without removing shared secrets
- Fix HelmService chartPath resolution for production Docker builds

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/Dockerfile

@@ -12,7 +12,12 @@ RUN npm run build
 # ---- Stage 2: Production ----
 FROM node:20-alpine AS production
 
-RUN apk add --no-cache dumb-init
+RUN apk add --no-cache dumb-init curl bash \
+ && curl -fsSL https://get.helm.sh/helm-v3.15.4-linux-amd64.tar.gz | tar xz -C /tmp \
+ && mv /tmp/linux-amd64/helm /usr/local/bin/helm \
+ && rm -rf /tmp/linux-amd64 \
+ && curl -fsSLO "https://dl.k8s.io/release/$(curl -fsSL https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl" \
+ && chmod +x kubectl && mv kubectl /usr/local/bin/kubectl
 
 ENV NODE_ENV=production
 WORKDIR /app
@@ -22,6 +27,7 @@ RUN npm ci --omit=dev && npm cache clean --force
 
 COPY --from=builder /app/dist ./dist
 COPY --from=builder /app/templates ./templates
+COPY --from=builder /app/helm ./helm
 
 RUN addgroup -S appgroup && adduser -S appuser -G appgroup
 USER appuser