feat: hostname resolver strategy and static hosts

Add the hostname resolver strategy. It connects by the NetBox name
instead of an IP, with resolver.hostname_domain appended to names
without a dot. Its position in the chain decides whether it is always
used or only as a fallback (e.g. [primary_ip, hostname]); names that
are not valid DNS hostnames fall through to the next strategy.

Add static hosts under hosts: for machines that are not in NetBox,
with address, user, port, tags, and their own SSH options. They are
checked before NetBox (by name or shortcut), never expire, survive
cache refresh and clear, and work without any NetBox configured. The
cache overlays them after every load and stores only their last use,
so they appear in completion, aliases, the TUI and its recent list.
SSH options merge global, static host, then rules; rules can match
kind: static. Manage them with netssh hosts list|add|remove and in
netssh configure, which can now also continue without NetBox.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -10,6 +10,8 @@
 - Add `netssh sftp` and `netssh scp`: host lookup, shortcuts, instances, default user and port, SSH options and rules, jump host, `--dry-run`, and completion work as for ssh. IPv6 addresses are bracketed for host:path.
 - Add named port forwards (`ssh.forwards` globally, per instance, and per rule), `netssh tunnel HOST NAME|SPEC...` (ssh -N with ExitOnForwardFailure), and `netssh --forward NAME`. Forwards are editable in `netssh configure` and completed in the shell.
 - TUI: `Ctrl+O` opens SFTP, `Ctrl+T` starts a tunnel with configured or ad hoc forwards.
+- Add the `hostname` resolver strategy: connect by the NetBox name (plus optional `resolver.hostname_domain`) instead of an IP, always or as a fallback after `primary_ip`.
+- Add static hosts (`hosts:`) for machines that are not in NetBox, with user, port, tags, and SSH options, managed with `netssh hosts list|add|remove` and in `netssh configure`. They are found before NetBox, work offline and without any NetBox, and support shortcuts, rules (`kind: static`), completion, aliases, sftp, scp, tunnels, and the TUI.
 - Fix options added by netssh landing after `--` (`netssh --no-jump -- host`), where ssh read them as the destination.
 
 ## v0.0.22