Why: Core T1 added ActivityCard, card.* events, HITL anchoring fields and seven
UI vocabularies; this repo's contracts.ts is the generated mirror.
Evidence: make contracts from Core main; frontend vitest 9/9 still green
(additive types, shape tests unaffected).
Impact: Types available for T2 inbox implementation; no behavior change.
Refs: Agent-System-Documents proposal 2026-09-30-ui-inbox-command-workspace