feat: infer scenarios and improve sandbox status UX

[Ker102]

Goal

Make
ullstate run easier to understand by defaulting scenario selection to auto-detection and improving sandbox status output.

Acceptance Criteria

• --scenario defaults to �uto and remains available as an explicit override for demos/tests.
• [ ]
  ullstate run examples/azure-public-blob --offline infers �zure-public-blob.
• Offline demos infer AWS, Kubernetes, Docker Compose, on-prem, and generic plan-review scenarios from their IaC files.
• sandbox status localstack-azure reports live Docker Compose/HTTP health when possible and still shows static metadata.
• README explains the model-less deterministic fallback and why a model endpoint is optional for demos.

Notes

Leave the PR open for evidence capture before merge.

[coderabbitai]

🔗 Related PRs

#10 - feat: run offline demos for all scenarios [closed]

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