feat: add Azurite fallback for Azure Blob scenario

[Ker102]

Goal

Provide a storage-only Azure Blob live validation path when LocalStack Azure Emulator entitlement is unavailable.

Acceptance Criteria

• Document Azurite as a fallback for the azure-public-blob scenario
• Add sandbox backend or adapter path for Azurite blob service
• Seed an intentionally public evidence blob/container locally
• Generated attack.py performs anonymous blob read before remediation
• After remediation, the read is blocked or clearly classified if Azurite cannot model the control
• Report labels the backend as Azurite fallback, not full Azure Resource Manager emulation

Technical Notes

Azurite should be scoped to Azure Storage behavior only. It must not be presented as a full Azure control-plane emulator.