Add Writing Desk paper copying and ink meter

docs/WRITING_DATA.md

@@ -86,5 +86,8 @@ panel, hold a blank Page in one hand and use an Ink Vial in the other. The
 server checks the held items, blank state, and sufficient ink before consuming
 anything. A stack of blank Pages yields exactly one Link Panel Page per use;
 if the inventory is full, the result is dropped instead of deleted. Symbol
-copying will be implemented by the Writing Desk. Link-property modifiers are
+copying is implemented by the Writing Desk: it previews a copy of the selected
+resolved page, then spends paper and ink only when that copy is taken. The
+desk's 16-unit ink meter refills from an Ink Vial when needed and returns a
+vanilla glass bottle. Link-property modifiers are
 deferred beyond this baseline flow.