Persist ordered book writing and restore Legacy book pages

docs/WRITING_DATA.md

@@ -40,6 +40,18 @@ a symbol reference or a baseline link-panel marker. `OrderedWriting` retains up
 to 256 entries in exact player-authored order. All three contracts have both
 persistent codecs and bounded network codecs.
 
+Assembled Descriptive Books store `OrderedWriting` schema version 1 alongside
+their Age reference. Books assembled in 0.3.7.2 saved writing as a bare list;
+that form still loads as version 1 without reordering or dropping unknown IDs.
+Older page-free books without writing continue to work unchanged. Copying a
+book copies its writing and Age reference; merely copying it never creates a
+new Age. The Book Binder creates the Age when its finished output is taken.
+The Descriptive Book screen can inspect the ordered pages by turning them from
+the bottom corners and identifies unresolved IDs using server-provided symbol
+metadata. Until Milestone 5, the
+saved symbols are informational only: Age creation uses the existing random
+fallback and does not apply them to generation.
+
 Removing a data pack never removes its IDs from saved writing. A missing ID is
 resolved as client-safe **Unresolved Symbol** display metadata while retaining
 the original namespaced ID for diagnostics and later restoration. This is