Expand link preview to cubic snapshot

README.md

@@ -26,9 +26,9 @@ right-clicking with an empty hand. Sneak-right-click with an empty hand to take
 the book back and restore the vanilla lectern. Breaking a Book Stand drops both
 the stored book and a vanilla lectern.
 
-Bound Linking Books request a server-validated 9-by-64-by-9 snapshot around
-their destination. The book renders a fixed 9-by-7-by-9 window centered on the
-link point as a rotating Ponder scene on the left page, backed by the
+Bound Linking Books request a server-validated 18-by-18-by-18 snapshot around
+their destination. The book keeps its target-centered close-up framing as a
+rotating Ponder scene on the left page, backed by the
 destination biome's sky color. The snapshot is visual only; the server
 independently validates every link.