feat: update response from broker endpoints

[emilylm]

📌 Summary

This PR fixes broker ID handling so responses and report payloads consistently distinguish entity IDs from submission IDs.

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🔄 Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)
• ✨ New feature (non-breaking change that adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🧹 Refactor (code change that neither fixes a bug nor adds a feature)
• 📚 Documentation update
• ⚙️ CI / build / tooling change

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🧩 Key Changes

• Broker endpoints now return canonical entity IDs in ClaimedEntity.id and submission IDs in ClaimedEntity.submission_id.
• Broker report processing now accepts explicit submission_id (with backward-compatible fallback to id) and validates entity/submission mismatches with 409.

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✅ Checklist

• Tests are passing locally / in CI
• New tests have been added for new or changed functionality
• Self-review completed
• Documentation updated (if needed)
• No sensitive data or secrets included

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🔍 Review Notes

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📎 Related Issues / Tickets

• Closes #
• Related to #

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