[+] improve cli_bootstrap.py with whl cache, venv_partial, packaging_t
1. add packaging_t: canonicalize_name, parse_whl_name_version, parse_req_spec;
2. add whl_cache_download: download missing wheels into .venv-whl-cache;
3. add check_host_prerequisites: verify pip and uv available on host;
4. add BootstrapSettings: whl_cache_path, uv_cache_dir, whl_cache_update;
5. add BootstrapSettings: uv_compile_allow_index, venv_partial;
6. add check_type helper for typed attribute access;
7. venv_partial recompiles with existing requirements.txt as constraints;
8. compile output goes to temp file, moved on success only;
9. guard typing_extensions import for bootstrap without venv;
LLM
77be19948d