fix(mcp): list tools return rows that say what a record is, not what it says (#4061)

list_tasks returned every row's to_dict(), body included: a project's todo list
came to 93-165k characters, past what an MCP client accepts inline, so the list
arrived as a file to page through (the #4045 failure, one call over).

- notes.brief_row: id, title, type, project, tags, updated_at; for tasks,
  status, kind, priority, milestone id and title; description, parent and due
  date only when set.
- milestones.titles_for: one query for the milestone titles a page of rows
  names.
- Brief rows on list_tasks, list_notes, get_milestone's steps, get_system and
  list_system_records. get_task / get_note / get_snippet read a record in full,
  and each docstring says so.
- tests/test_list_rows_brief.py pins the ceiling: 100 rows of ~5k-character
  step plans stay under 40k characters.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

src/scribe/mcp/tools/notes.py

@@ -44,6 +44,9 @@ async def list_notes(
     Prefer `search` for a pure lookup — it returns scores and reaches
     everything readable; this adds the lifecycle filters on top.
 
+    Each row says what the note is — id, title, description, type, project,
+    tags, updated_at — and not what it says: read one in full with get_note(id).
+
     Args:
         project_id: Scope to one project. PASS THE ACTIVE PROJECT'S ID whenever a
             project is in scope so you list that project's notes, not every
@@ -60,7 +63,7 @@ async def list_notes(
         limit=max(1, min(limit, 100)),
         offset=max(0, offset),
     )
-    return {"notes": [n.to_dict() for n in rows], "total": total}
+    return {"notes": [notes_svc.brief_row(n) for n in rows], "total": total}