feat: show tool count in context command UI

[Tarquinen]

Summary

• Display tool count in the context breakdown UI: Tools (X) where X is tools remaining in context
• Uses dynamic label padding to maintain alignment regardless of tool count digits

Example Output

System     27.1% │████████                      │   15K tokens
User        2.0% │▓                             │  1.1K tokens
Assistant  35.7% │▒▒▒▒▒▒▒▒▒▒▒                   │ 19.7K tokens
Tools (33) 35.3% │░░░░░░░░░░░                   │ 19.5K tokens