- Remove old_webclient directory and /static mount from main.py
- Add shutdown handler in main.py to close all SSH pooled connections
- Decouple agent.py from todo module internals:
  - Add public API to navi/tools/todo.py: get_task_snapshot, get_failed_steps,
    get_progress_message, set_tasks, render_todo_lines
  - Replace all direct _plans/_STATUS_ICON/_Task imports in agent.py with API calls
- Wrap run_ephemeral in try/finally to restore _sid_var and _model_var after subagent

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>