Parse the todo_tool result summary to display completion progress in
CLI tool preview lines:
Read: ┊ 📋 plan 3/4 task(s) 0.5s
Update: ┊ 📋 plan update 3/4 ✓ 0.5s
Create: falls back to plain count when no completed tasks
Falls back gracefully to the existing 'N task(s)' format when the
result is missing, malformed, or has no completed items.
Originally proposed in PR #17194 by Albert.Zhou; salvaged onto current
main.
Co-authored-by: Albert.Zhou <albert748@gmail.com>
