Stale config entry fix, cleanup hardening and lint modernization.
- Fix deploy resolving the typed host through a stale
HostNamewhen overwriting a managed entry (common after reflashing a device). The old block is now removed just before deploy (#6, #7) - Clean up the generated key pair when deploy or the config write fails partway
- Adopt ruff 0.16 default lint rules: modern type annotations, explicit subprocess
check, timezone-aware date stamp - Align
--helpexample descriptions into one column - Polish PyPI metadata and README: sharper summary, sidebar links, PATH tip for pip installs