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/note_usage.py

@@ -54,23 +54,22 @@ class NoteUsageEvent(Base, CreatedAtMixin):
     # A CONVENTION, not a fixed vocabulary: `mcp_<tool>` for an agent call,
     # `rest_<kind>` for a human opening a detail view, and a bare name for a
     # hook or background surface ('auto_inject', 'write_path_place',
-    # 'write_path_semantic'). This comment deliberately no longer lists the
-    # members — the previous list had gone stale, naming 'rest_note' that
-    # nothing wrote while omitting sources that existed, and a half-true
-    # enumeration reads as authoritative in exactly the way that misleads
-    # (#2476). `grep -rn record_pulled\\\|record_surfaced src/` is the
+    # 'write_path_semantic'). This comment deliberately does not list every
+    # member — such a list goes stale, naming sources nothing writes while
+    # omitting ones that exist, and a half-true enumeration reads as
+    # authoritative in exactly the way that misleads. `grep -rn record_pulled\\\|record_surfaced src/` is the
     # authoritative list, and unlike a comment it cannot drift.
     #
     # The mcp_/rest_ split is load-bearing. "Is this dead weight?" is served by
     # any pull; "was that injected line useful?" is served by AGENT pulls only,
-    # so never aggregate across the prefix without saying why (#1038, #2085).
+    # so never aggregate across the prefix without saying why.
     source: Mapped[str] = mapped_column(Text, nullable=False)
 
     # The project the READER was in when this happened — not the project the
     # record belongs to, which is already on `notes.project_id`. The whole
     # point is the comparison between the two: a record opened somewhere other
     # than where it was written is the evidence that it TRANSFERRED, which is
-    # the claim the lesson kind rests on (milestone 385) and the one thing
+    # the claim the lesson kind rests on and the one thing
     # RetrievalLog could half-answer and this table could not answer at all.
     #
     # Nullable, and null is ordinary rather than historical. A surfacing arm