fix(family): the owed task is tagged by the matching System only, and the ground fixtures build without duplicate keys (#4990)

assess_family_adoption took system_ids for the task it files, which made
the family tool module look like a System-tagging door and tripped the
parity registry. It is not one: the owed task is tagged to the project's
System matching the idea's canonical area, and update_task retags it.
The unit test for each conflict ground passed evidence/conditions twice.

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

src/scribe/mcp/tools/family.py

@@ -253,7 +253,6 @@ async def assess_family_adoption(
     reason: str,
     evidence: list[str] | None = None,
     precedent_ids: list[int] | None = None,
-    system_ids: list[int] | None = None,
 ) -> dict:
     """Answer one canon family idea for one project. YOU decide; nobody
     approves. Judge in this order and stop at the first that holds:
@@ -268,8 +267,10 @@ async def assess_family_adoption(
     3. adopted — it applies and the project does it. `evidence` names where
        (a file, a commit, a task, a CI run).
     4. owed — none of the above. A task is filed in THIS project naming the
-       gap and the reference implementation for its language. Nothing edits
-       another repository; the project picks the task up itself.
+       gap and the reference implementation for its language, filed under
+       the project's System matching the idea's area (retag it with
+       update_task if that guess is wrong). Nothing edits another
+       repository; the project picks the task up itself.
 
     Read get_family_adoption first: answer consistently with its precedents
     unless this project differs in a way you can name in `reason`. The
@@ -286,11 +287,10 @@ async def assess_family_adoption(
         reason: why — required for every outcome.
         evidence: where it is done (required for adopted), or what you checked.
         precedent_ids: earlier family decisions you followed, if any.
-        system_ids: Systems for an owed task. Omit to match the idea's own.
     """
     return await adoption_svc.assess(
         current_user_id(), project_id, idea_id, outcome=outcome, reason=reason,
-        evidence=evidence, precedent_ids=precedent_ids, system_ids=system_ids,
+        evidence=evidence, precedent_ids=precedent_ids,
     )