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_shared_write_access.py

@@ -85,7 +85,7 @@ async def test_merge_requires_write_on_target():
 
 @pytest.mark.asyncio
 async def test_merge_skips_sources_owned_by_someone_else():
-    """Cross-owner merge stays out of scope (#231): a source belonging to a
+    """Cross-owner merge stays out of scope: a source belonging to a
     different owner than the target is skipped, not silently folded in and
     trashed."""
     from scribe.services import snippets as svc