Give every view a TSIG key that selects it

Each view's match-clients starts with "key jarl-view-NAME" (after
"!key" for the views listed after it), so a query signed with a view's
key lands in that view from any address. The secrets are derived from a
random seed in Jarl's database. The delegation check signs its queries
to this server's own addresses with the key of the zone's view: before,
they got whichever view matched the server's address, usually internal.
jarl view key / GET /views/{id}/key show a key for dig -k (tsig:write,
audited). jarl-view- key names are reserved; the importer drops view
keys from a configuration Jarl wrote.

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

docs/cli.md

@@ -368,6 +368,7 @@ jarl view order internal external
 jarl view update external --match-clients "!homelab,any"
 jarl view delete old [--cascade]
 jarl view color internal green                # web UI colour; "default" resets it
+jarl view key external [--named-conf]         # the key that selects the view (dig -k), docs/views.md
 
 jarl acl create homelab 192.168.1.0/24 10.10.0.0/16 localhost
 jarl acl update homelab --add 10.20.0.0/16 --remove 10.10.0.0/16