Add book GUI and Ponder preview foundation

docs/PORTING.md

@@ -48,6 +48,11 @@ the symbol grammar is introduced.
 - [ ] Return-link creation as part of Descriptive Book travel.
 - [x] Lectern-to-Book-Stand conversion, displayed book, activation, removal,
   persistence, and drops.
+- [x] Book-screen foundation with server-authoritative naming, binding, and
+  explicit link activation.
+- [x] Ponder dependency and isolated destination-preview level boundary.
+- [ ] Server-provided destination snapshots rendered as rotating Ponder scenes.
+- [ ] Book Stand floating names and opening the stored book screen.
 - [ ] Automated in-game tests for binding, persistence, and travel.
 
 The temporary shapeless Linking Book recipe makes the linking subsystem easy
@@ -69,6 +74,17 @@ initial cooldown used Minecraft's item-type cooldown system, which delayed all
 Linking Book stacks at once. Version 0.1.3 removes that cooldown to match the
 legacy behavior.
 
+Version 0.1.4 moves Linking Book binding and travel behind a book screen. The
+client requests an action, while the server revalidates the held book and owns
+all changes to its destination and custom name. Descriptive Book Age references
+now carry a display name alongside their stable UUID, with backward-compatible
+decoding for existing UUID-only data.
+
+The preview code is separated behind a renderer interface and uses an isolated
+Ponder level. The first iteration supplies the animated loading boundary; the
+next iteration will add server-authoritative snapshot transport and populate
+that level with the destination blocks.
+
 ## Version policy
 
 Versions follow `x.y.z`: