content: tree-wide revision diff (772/772)

content/diff + diff-versions enumerated ids top-level only (doc-ids/
doc-find), so diffs of documents with sections missed every nested add/
remove/change. Now via doc-tree-ids + doc-deep-find; sections excluded from
:changed (no own content), still reported in :added/:removed. Flat-doc
diffs unchanged. +9 store tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/content/scoreboard.md

@@ -35,7 +35,7 @@ _Generated by `lib/content/conformance.sh`_
 | data | 25 | 0 | 25 |
 | wire | 11 | 0 | 11 |
 | validate | 23 | 0 | 23 |
-| store | 37 | 0 | 37 |
+| store | 46 | 0 | 46 |
 | snapshot | 20 | 0 | 20 |
 | crdt | 34 | 0 | 34 |
 | crdt-tree | 21 | 0 | 21 |
@@ -45,4 +45,4 @@ _Generated by `lib/content/conformance.sh`_
 | md-import | 38 | 0 | 38 |
 | md-doc | 12 | 0 | 12 |
 | fed | 20 | 0 | 20 |
-| **Total** | **763** | **0** | **763** |
+| **Total** | **772** | **0** | **772** |