fix(family): a decision read as precedent says its reason once - to_brief for precedents and idea history; the decision log keeps the full row (#5131)

Each decision stored its reason three times (reason, before.reason, after.reason)
and a promotion carried the whole criteria reasoning in evidence. Precedents
(assess, promote, get_family_adoption, get_family_idea) and get_family_idea's
history now serve FamilyDecision.to_brief(): reason once, before/after as status,
canon_version and platforms, evidence as the cited list. list_family_decisions
and the decision echoed back by a write keep to_dict. The precedent count was
already bounded at five.

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

src/scribe/services/family.py

@@ -211,7 +211,8 @@ async def get_idea(user_id: int, note_id: int) -> dict | None:
             "platforms": await _platform_slugs(session, note_id),
             "topic": await _topic(session, user_id, idea.topic_id, rules=True),
             "adoptions": counts,
-            "decisions": [_decision_dict(d) for d in decisions],
+            # Brief: the history is read in bulk; the full rows are list_decisions (#5131).
+            "decisions": [d.to_brief() for d in decisions],
             "undoable_decision_id": _undoable_id(decisions),
         })
     out["criteria"] = list(CRITERIA)
@@ -383,8 +384,8 @@ async def precedents(user_id: int, note_id: int, limit: int = 5) -> list[dict]:
     for score, n in ranked:
         d = decisions.get(latest.get(n.id))
         if d is not None:
-            item = _decision_dict(d, n.title)
-            item["similarity"] = round(float(score), 3)
+            item = {**d.to_brief(), "idea_title": n.title,
+                    "similarity": round(float(score), 3)}
             out.append(item)
     return out