Sets from Jarl: sets holding the addresses of names in Jarl

A set can take its addresses from Jarl: every A and AAAA record of its
names (NAME@VIEW), CNAMEs followed within Jarl's zones in the same view.
housecarld reads them every jarl.refresh and after each change, keeps
only the addresses within the zones and networks the set allows, and
keeps what it last read (saved in the database and the boot ruleset)
while Jarl can't be reached. A change of the addresses applies the
ruleset again without a history entry and is audited (set.jarl).

hc set add --jarl --within, hc set jarl; the kind "from Jarl" and
Addresses… on the Sets page; GET /sets/{name}/jarl and /jarl/refresh;
validation codes set_jarl_*, status warnings jarl_*; docs/jarl.md.
e2e phase with scripts/fakejarl.

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

internal/render/render.go

@@ -52,6 +52,9 @@ type Options struct {
 	DeviceSets map[string][]Element
 	// Bans are the ban lists' active bans, added to their sets.
 	Bans []Ban
+	// JarlSets are the Jarl sets' addresses (set name → addresses, both
+	// families), as Jarl gave them and within allows.
+	JarlSets map[string][]string
 	// Shadow renders for shadow mode: nothing is blocked, rejected,
 	// translated or changed (see the package comment).
 	Shadow bool
@@ -186,6 +189,10 @@ func (r *renderer) sets() {
 			}
 			continue
 		}
+		if s.Jarl != nil {
+			r.jarlSet(s)
+			continue
+		}
 		has4, has6 := s.Families()
 		for _, v6 := range []bool{false, true} {
 			if v6 && !has6 || !v6 && !has4 {
@@ -197,6 +204,26 @@ func (r *renderer) sets() {
 	}
 }
 
+// jarlSet declares a Jarl set's two sets with the addresses it has now
+// (none yet: empty, so its rules match nothing).
+func (r *renderer) jarlSet(s *model.AddressSet) {
+	for _, v6 := range []bool{false, true} {
+		var elems []string
+		for _, e := range r.opt.JarlSets[s.Name] {
+			if a, err := model.ParseAddress(e); err == nil && a.IsV6() == v6 {
+				elems = append(elems, a.String())
+			}
+		}
+		if len(elems) == 0 {
+			r.w.emit("set "+s.Name, "\tset %s { type %s; }", setName(s.Name, v6), addrType(v6))
+			continue
+		}
+		// Single addresses: no interval flag, so they stay as they are
+		// (auto-merge would join neighbours into ranges).
+		r.w.emit("set "+s.Name, "\tset %s { type %s; elements = { %s } }", setName(s.Name, v6), addrType(v6), strings.Join(elems, ", "))
+	}
+}
+
 func (r *renderer) elements() {
 	names := make([]string, 0, len(r.opt.Elements))
 	for n := range r.opt.Elements {