observe: stamp Entra Agent ID on traces + publish evidence bundle

[placerda]

Context

The accelerator produces rich inner-loop telemetry (OTel traces) and eval/posture results, but none of it is correlatable to the agent's identity in the fleet-level Agent 365 observability plane.

Goal

Stamp the Entra Agent ID onto emitted traces and publish an evidence bundle (eval + doctor posture) linked to the agent's appId.

Scope

• Inject the Entra Agent ID as an OTel resource attribute on emitted traces.
• Generate a versioned evidence bundle (eval scores + doctor posture) referencing the appId.

Approach

• Add gen_ai.agent.id to the resource attributes of the existing OTel exporter.
• Emit the bundle as a stable versioned JSON artifact referencing the blueprint.
• Do not depend on an Agent 365 ingestion API (not public yet). We publish the artifact; the control plane consumes it.

Acceptance criteria

• Emitted traces carry the Entra Agent ID attribute.
• Evidence bundle is generated and linked to the appId.
• The handshake (what we publish, how it is consumed) is documented.

Notes

• Depends on the appId produced by the ship auto-register issue.
• Last of the three (build after register works).

Out of scope

• Purview/audit ingestion internals (Microsoft-owned).