chore: add TODO to .gitignore

Ignore TODO file from version control as it's used for
temporary task tracking during development.

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

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

.gitignore

@@ -124,6 +124,7 @@ logs/
 temp-*.txt
 *.tmp
 *.temp
+TODO
 
 # Backup files
 *.bak