fix(deploy): support low-disk AWS code-only rebuilds

[danyellambert]

Summary

• Clean safe Docker data before code-only preflight
• Make the disk threshold advisory instead of blocking
• Stop the compose stack without removing volumes before rebuild
• Prune build cache, stopped containers and unused images before Docker build
• Preserve persistent Docker volumes, including Caddy TLS data

Validation

• AWS CD execute passed on branch fix/aws-low-disk-code-only-rebuild
• Deploy completed successfully through SSM tunnel
• Containers came back healthy
• Persistent dirs and Docker volumes were preserved
• Product API health returned ok=true