docs: consolidate PR hygiene check from 3 commands to 2

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CLAUDE.md

@@ -53,7 +53,6 @@ Before creating a PR, adding a skill, or preparing any contribution, you MUST re
 Before pushing or creating a PR, run these checks and show the output to the user for approval:
 
 ```bash
-git diff upstream/main --name-only HEAD
 git diff upstream/main --stat HEAD
 git log upstream/main..HEAD --oneline
 ```