chore: Organize .gitignore with Claude Code section

- Remove duplicate .claude/settings.local.json entry
- Add dedicated "Claude Code" section in .gitignore
- Improve file organization and readability

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -44,4 +44,6 @@ flagged/
 # OS
 .DS_Store
 Thumbs.db
+
+# Claude Code
 .claude/settings.local.json