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>

internal/server/routes.go

@@ -52,6 +52,7 @@ func (s *Server) routes() {
 	m.HandleFunc("POST "+p+"/views", s.authed(s.createView))
 	m.HandleFunc("POST "+p+"/views/order", s.authed(s.reorderViews))
 	m.HandleFunc("GET "+p+"/views/{id}", s.authed(s.getView))
+	m.HandleFunc("GET "+p+"/views/{id}/key", s.authed(s.viewKey))
 	m.HandleFunc("PATCH "+p+"/views/{id}", s.authed(s.updateView))
 	m.HandleFunc("DELETE "+p+"/views/{id}", s.authed(s.deleteView))
 	m.HandleFunc("PUT "+p+"/views/{id}/color", s.authed(s.setViewColor))