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_integration_backup_file_ordering.py

@@ -1,11 +1,11 @@
 """Real-Postgres check that the full export is ORDERED, so the backup file
-deduplicates between runs (milestone 523).
+deduplicates between runs.
 
 Only Postgres shows this. An unordered select returns rows in heap order, and
-an UPDATE writes the row's new version at the end of the heap — so before
-export_full_backup ordered its queries, editing one old note moved it to the
-bottom of `notes`. Every byte after its old place shifted, and a restic run
-over the next backup stored most of the table again. A mocked session returns
+an UPDATE writes the row's new version at the end of the heap — so without an
+ORDER BY in export_full_backup, editing one old note moves it to the bottom of
+`notes`. Every byte after its old place shifts, and a restic run over the next
+backup stores most of the table again. A mocked session returns
 whatever order it was handed and could never catch it.
 """
 import io