docs(6209): forty test files — design cascade and stylesheet, embeddings, family canon, forge, backup round trips, inception, placement, platforms, moments, rule move and verification, search scope, facets

Module and test docstrings state what is pinned without the record number
or step that introduced it. Incident accounts become the failure shape in
the present tense: the pipefail head, the code_shapes import, the export
order, the facet dialects, the cross-kind repeat, the write-once kind.

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

tests/test_check_design_tokens.py

@@ -1,4 +1,4 @@
-"""The CI-side token check (#2277).
+"""The CI-side token check.
 
 The checker is stdlib-only and lives in scripts/ so CI can run it without an
 install, so these tests import it by path rather than as a package.
@@ -45,7 +45,7 @@ def test_declarations_after_a_comment_are_not_lost():
 
 
 def test_the_supersedes_block_is_read_from_the_sheet_not_hardcoded():
-    """Rule #115: the checker must know nothing about any install's palette.
+    """The checker knows nothing about any install's palette.
     Everything it enforces comes out of the stylesheet it is pointed at."""
     assert check.superseded_literals(SHEET) == {
         "#fff": "--fs-text-primary",