Return packed availability claim payloads

[aledefra]

Summary

• Add from_epoch, to_epoch, and packed_availabilities to oracle availability responses.
• Sign the compact claim payload produced by the blockchain SDK.
• Keep expanded epochs and epochs_vals in the API response for inspection.

Validation

• python -m py_compile extensions/business/oracle_management/oracle_api.py

[Copilot]

Pull request overview

This PR updates the oracle availability API payload to include a compact, SDK-produced claim representation (range + packed availability bytes) alongside the existing expanded epochs / epochs_vals, and signs the compact claim payload for EVM verification.

Changes:

• Extend __get_signed_data output with from_epoch, to_epoch, and packed_availabilities.
• Update the signing path to surface the compact claim fields returned by the blockchain SDK.
• Keep expanded epoch lists in the response for inspection/debugging.

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