[Task]: Persist and expose governance metadata

[rian-be]

Summary

Turn intent classification fields into runtime-usable governance data.

Goal

Persist and expose Tags, Metadata, and EstimatedBlastRadius so governance decisions and query workflows can use them consistently.

Problem

These fields already exist in the public model, but they are still under-realized at runtime. Without persistence and query integration, they remain descriptive data rather than actionable governance inputs.

Scope

• Persist Tags, Metadata, and EstimatedBlastRadius into governance and audit/history records
• Expose these fields through governance query contracts
• Support filtering and reporting based on governance metadata
• Enable policy decisions or governance rules that rely on persisted metadata

Design Expectations

• Metadata should be persisted in a way that remains queryable and stable across providers.
• Blast radius should be usable as governance classification, not just passive annotation.
• Query surfaces should make metadata-oriented filtering first-class.
• Runtime semantics should stay clear about which metadata is request-level vs execution-level.

Acceptance Criteria

• Governance metadata survives persistence and round-trips through query APIs
• Query contracts support metadata-oriented filtering
• Metadata fields are visible in governance examples or documentation where relevant
• Governance rules can use the persisted metadata surface consistently

Non-Goals

• This issue does not define UI/reporting products
• This issue does not add typed side effects by itself
• This issue does not replace request decision history with metadata-only reasoning

Notes

These fields already exist in the public model. This issue closes the runtime gap around them.