infra: add persistent uploads volume and configure Caddy to serve static images

- Add named Docker volume `uploads` mounted at /app/public/uploads in app container
- Share same volume with Caddy at /srv/uploads for direct static file serving
- Add Caddy `handle /uploads/*` block so images bypass Next.js (standalone mode does not serve runtime public files)
- Create uploads directory with correct nextjs:nodejs ownership in Dockerfile
- Add mkdir safeguard in entrypoint.sh

app/Dockerfile

@@ -31,6 +31,7 @@ COPY --from=builder /app/scripts ./scripts
 COPY entrypoint.sh ./
 RUN chmod +x entrypoint.sh
 RUN apk add --no-cache postgresql-client openssl
+RUN mkdir -p /app/public/uploads && chown nextjs:nodejs /app/public/uploads
 USER nextjs
 EXPOSE 3000
 ENTRYPOINT ["./entrypoint.sh"]