Update CLI and roadmap documentation; clean up code

- Revised CLI documentation to clarify the sequence of operations for the `up` command and updated the status of features.
- Enhanced the roadmap with completed tasks marked as done.
- Removed unused import in clone_ext.py for cleaner code.
- Added assertions in test_bootstrap.py to ensure correct script generation and validate the presence of autocompletion data.

src/gpu_rent/remote/clone_ext.py

@@ -3,7 +3,6 @@
 from __future__ import annotations
 
 import json
-import os
 import subprocess
 import sys
 from pathlib import Path