Q160: a goal's pace is measured against its target date, and claimed only when it has one

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/shared/domain.ts

@@ -172,6 +172,8 @@ export interface GoalRecord {
   ownerAgentId: string | null;
   /** Set when the goal's review loop stopped without a decision. */
   stalledReason: string | null;
+  /** When the goal is planned to be reached; null when no target date was set. */
+  dueAt: string | null;
   createdAt: string;
   updatedAt: string;
 }