[v1.x] Remove AI attribution commit rule from CLAUDE.md

Drop the two CLAUDE.md bullets (Commits and Pull Requests sections)
that told agents never to mention a co-authored-by trailer or the tool
used to create a commit message or PR.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016VBdiP9GZpoyZ41ZSZ9YRZ

Author: claude

CLAUDE.md

@@ -44,18 +44,12 @@ This document contains critical information about working with this codebase. Fo
   git commit --trailer "Github-Issue:#<number>"
   ```
 
-- NEVER ever mention a `co-authored-by` or similar aspects. In particular, never
-  mention the tool used to create the commit message or PR.
-
 ## Pull Requests
 
 - Create a detailed message of what changed. Focus on the high level description of
   the problem it tries to solve, and how it is solved. Don't go into the specifics of the
   code unless it adds clarity.
 
-- NEVER ever mention a `co-authored-by` or similar aspects. In particular, never
-  mention the tool used to create the commit message or PR.
-
 ## Python Tools
 
 ## Code Formatting