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_record_batch.py

@@ -1,4 +1,4 @@
-"""Real-Postgres proof that a batch create cannot be interfered with (#4016).
+"""Real-Postgres proof that a batch create cannot be interfered with.
 
 What mocks cannot show: that the ids a placeholder is rewritten to are the ids
 the rows actually got, that two batches running at the same time each cite