docs(skills): stop printing a refusal string the sharing gate no longer emits

`data-hooks.md` quoted the by-id write gate's message verbatim. That sentence is
now end-user copy rendered in the caller's locale, so a hook author reading the
doc would string-match prose that varies by locale. The fence names the shape
and points at the stable channel (the error's code) instead.

Token-neutral by construction: the published-bundle ratchet reads 12611 against
a ceiling of 12611 (+0), so this correction spends no context budget.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0194kbQJxUvv2yvsGRtuXpP5

Author: claude

skills/objectstack-data/references/data-hooks.md

@@ -495,7 +495,7 @@ whoever is elevated. If the acting user cannot edit the target (e.g. it is
 `public_read`), the write throws:
 
 ```
-FORBIDDEN: insufficient privileges to update <object> <id>
+FORBIDDEN: <a localized sentence; match on code, not prose>
 ```
 
 **An admin is not automatically exempt** — the gate is `canEdit`, driven by the