Updates InboundMessage to surface the three channel-envelope enrichment
fields (peer_name, peer_role, agent_card_url) as typed attributes instead
of requiring callers to read them from msg.raw["data"]. Fields default to
"" when absent so existing callers are unaffected.
Also marks KI-001 (RemoteAgentClient does not implement inbound A2A server)
as resolved — A2AServer, PushDelivery, and PollDelivery all ship in the
current codebase; the known-issues.md entry was stale.
New tests:
- test_parse_activity_row_enrichment_fields
- test_parse_activity_row_enrichment_fields_absent
- test_parse_activity_row_enrichment_fields_null_becomes_empty
- test_parse_activity_row_enrichment_in_canvas_user_row
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>