Update .cursorrules to strip PR footers after creation

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: Cursor

.cursorrules

@@ -10,6 +10,7 @@
 
 ## Pull Requests
 - Do NOT add "Made with Cursor" or similar footers to PR descriptions
+- After creating a PR with `gh pr create`, immediately run `gh pr edit <number> --body "..."` to ensure no footer was appended
 - Keep PR descriptions concise and focused on the changes
 
 ## Code Style