docs(6209): the remaining test files — lessons, reply moment and shape, retrieval specs and scopes, rule doors and judgments, services, snippets, search scope; five tests renamed to their property

Docstrings, section headers and assertion messages drop the record number,
milestone or step that introduced the behaviour, and incident accounts are
restated as the present-tense failure shape. A dead pointer to a design doc
that is not in the repo is removed.

Renamed to the property they check:
  test_the_old_shape_would_be_caught -> test_a_rank_then_scope_query_is_caught
  test_a_ledger_repeat_no_longer_produces_that_case_at_all -> test_a_ledger_repeat_is_counted_not_withheld
  test_the_header_no_longer_promises_once_per_session -> test_the_header_explains_the_seen_marker
  test_the_portal_case_no_longer_stamps_one_canon_onto_a_whole_file -> test_one_canon_is_not_stamped_onto_a_whole_file
  test_the_repos_own_prose_no_longer_defines_with -> test_the_repos_own_prose_does_not_define_with
  test_the_original_regression_create_note_with_content -> test_the_real_server_refuses_content_on_create_note

Fixture and example ids stay: "note 5" in a supersession chain, "rule 156"
in an illustrative question, `#2275` as the hex-versus-citation case,
`#3244` as the example of a bare number, fixed dates in date-filter tests.

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

tests/test_rule_via_lesson.py

@@ -1,4 +1,4 @@
-"""A rule reached through its lessons (milestone 440, #4633).
+"""A rule reached through its lessons.
 
 The step runs after each of the three rule arms. These pin, with the database
 and the embedder stubbed: that nothing is searched when no lesson carries a
@@ -125,7 +125,7 @@ async def test_a_failure_brings_no_rule_and_raises_nothing():
 
 @pytest.mark.asyncio
 async def test_the_step_follows_the_arm_on_its_query_and_skips_what_it_named():
-    """One composer for all three rule builders (milestone 456 step 6): the
+    """One composer for all three rule builders: the
     via-lesson step searches with the query the arm searched with, skips the
     session's ledger and every rule the arm's band named, and its lines and
     fresh ids join the arm's — while `shown_rule_ids` stays the direct band."""
@@ -153,9 +153,9 @@ async def test_a_blank_prompt_runs_neither_the_arm_nor_the_step():
 
 
 def test_only_the_composer_runs_a_rule_arm_or_the_via_lesson_step():
-    """Structural (rule 167): every rule builder goes through `_rule_moment`,
-    so a builder that runs the arm or the via-lesson step by hand again is the
-    copy this step removed coming back — and a count is what lets it fail."""
+    """Structural: every rule builder goes through `_rule_moment`, so a
+    builder that runs the arm or the via-lesson step by hand is a second copy
+    of the composer — and a count is what lets it fail."""
     import ast
     from pathlib import Path