docs(6206): the remaining models, routes, mcp/tools/repos and config comments drop citations

A shipped tool docstring (mcp/tools/repos bind_repo) cited this instance's
"rule 1: dev is home"; it now says what a dev-branch project should do.
routes/knowledge, routes/tasks, routes/systems and models/retrieval_log state
the property each guards rather than the bug that once broke it.

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

src/scribe/models/canonical_system.py

@@ -7,7 +7,7 @@ from scribe.models.base import SoftDeleteMixin, TimestampMixin, iso
 
 class CanonicalSystem(Base, TimestampMixin, SoftDeleteMixin):
     """A GLOBAL area name — the shared vocabulary every project's Systems
-    can point at (milestone 307, decision note 3026).
+    can point at.
 
     A `System` is per-project and NOT NULL on project_id, so nothing outside a
     project can reference one: a rule that applies across projects has no way