refactor(retrieval): the notes arms run on the one pipeline - auto_inject, its reuse and lesson slots, the write path by meaning, and rule_via_lesson are specs (milestone 456 step 4, #4906)

retrieval_pipeline gains the notes half: NoteArm / NoteSlot / NoteMoment /
NoteIO / NoteResult and run_note_arm, which writes once the stages both
notes arms copied: search, withhold this response's own menu (#3739),
fresh/repeat split, the call row before any return (#3497, #3752), the
band, the reserved slots in their order (reuse evicts, lesson extends),
and the surfacing rows. The note renderer (_record_kind, _menu_name,
_menu_passage, the seen pointer, menu_entry) moves with it, and
run_via_lesson_arm takes rule_via_lesson.

Behaviour-preserving, with flags for today's differences: notes still log
BEFORE the band and rules after it (step 7's question). One deliberate
change: a notes arm now fails open like the rule arms, so a failing
search costs its lines and no longer the whole hook response.

The I/O is resolved from plugin_context at call time (_note_io), so the
existing patches keep working. The review re-run reads the AUTO_INJECT
spec instead of restating it, and its guard now compares the two live
searches. The registry declares the pipeline's notes fan-out sites.

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

tests/test_retrieval_surfaces.py

@@ -70,9 +70,9 @@ def test_every_surface_name_is_a_real_telemetry_source():
     # The rule arms record through the one pipeline (milestone 456), where
     # `source` is the spec's own field — so for them the spec IS the string
     # `record_retrieval` receives, and the join key is checked against it.
-    from scribe.services.retrieval_pipeline import RULE_ARMS
+    from scribe.services.retrieval_pipeline import NOTE_ARMS, RULE_ARMS
 
-    via_pipeline = {arm.source for arm in RULE_ARMS}
+    via_pipeline = {arm.source for arm in (*RULE_ARMS, *NOTE_ARMS)}
     missing = [
         s.name for s in rs.SURFACES.values()
         if f'source="{s.name}"' not in blob