Different blocking for different devices: steps and client groups

Client groups put devices (addresses, networks, or ACLs of them) at a
blocking step: off (only your rules), normal (the default), or steps
added above it, each including the lists of the steps below. Lists
start at a step. In each view, a gate policy zone in front of a step's
lists lets the devices below that step through (rpz-client-ip triggers
with rpz-passthru), so every list is still loaded once. The IPv6 part
of a gate leaves the IPv4-mapped range out: named matches IPv4 clients
as ::ffff:a.b.c.d.

Web UI: a Devices panel on the Blocking page and a step on each list.
CLI: jarl block step, jarl block group, jarl blocklist --step. API:
/blocking/steps, /blocking/groups. Database schema 8.

Also: copying the state kept empty lists as empty (not nil), so
reverting a changeset no longer adds restore operations for unchanged
blocklists, rules and views.

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

internal/engine/refs.go

@@ -152,6 +152,11 @@ func FindRefs(st *model.State, kind refKind, name string) []string {
 			out = append(out, "view "+v.Name)
 		}
 	}
+	for _, g := range st.SortedClientGroups() {
+		if _, hit := rewriteElements(g.Members, kind, name, name); hit {
+			out = append(out, "client group "+g.Name)
+		}
+	}
 	var opts []string
 	for _, o := range st.Options {
 		stmt, err := namedconf.ParseOptionValue(o.Name, o.Value)
@@ -188,6 +193,12 @@ func renameRefs(st *model.State, kind refKind, old, new string, c *applyCtx) {
 			v.Touch(c.user(), c.now)
 		}
 	}
+	for _, g := range st.ClientGroups {
+		if l, hit := rewriteElements(g.Members, kind, old, new); hit {
+			g.Members = l
+			g.Touch(c.user(), c.now)
+		}
+	}
 	for _, o := range st.Options {
 		stmt, err := namedconf.ParseOptionValue(o.Name, o.Value)
 		if err != nil {