Add curl to Docker image for Swarm health checks

The runner stage needs curl for the health check command.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Dockerfile

@@ -35,6 +35,9 @@ WORKDIR /app
 
 ENV NODE_ENV=production
 
+# Install curl for health checks
+RUN apk add --no-cache curl
+
 RUN addgroup --system --gid 1001 nodejs
 RUN adduser --system --uid 1001 nextjs