List Saved Sessions

1. Determine the current project: the basename of the git repository root (git rev-parse --show-toplevel), or of the working directory outside a repo, so subfolders of one repo share state.
2. Read the contents of the ~/.claude_states/<project>/ directory.
3. If the directory does not exist or is empty, output: "No session checkpoints found for this project."
4. If files exist, list them clearly as a bulleted list, stripping out the .md extension so only the session name is visible.
5. Ask me: "Which session would you like to load?"
6. Wait for my response. When I reply with a name, follow /checkpoint-load with that name (/loadout:checkpoint-load if installed as a plugin), including its name checks and sendit- routing.