- Add fsnotify-based file watcher that auto-reloads extensions on .go
file changes in autoloaded dirs with 300ms debounce
- Add /reload-ext built-in command (alias /re) for manual reload
- Add Agent.SetExtraTools() so extension tools update on reload
instead of being baked in at agent creation time
- Run reload async via tea.Cmd to avoid prog.Send() deadlock when
extension handlers call ctx.Print() during SessionStart/Shutdown
- Wire watcher lifecycle into cmd/root.go with graceful shutdown