Add WireGuard, DNS and more to the web UI and router-setup

Web UI: a WireGuard page (tunnels, peers, keys made on the router, client
configs with a QR code, import of wg-quick configs, live status), a DNS page
(records, wildcards, forward zones), interface dropdowns with VLAN devices,
IPv6 options and a local domain. router-setup asks about VLANs, IPv6 and
the domain. The router publishes its own name in DNS and hands the local
domain to DHCP clients; wg and jq are on the router. Includes a script
that takes over antigua's tunnels.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AeFqV9dZrK6nipHkPfyM4F

pkgs/router-webui/dashboard.go

@@ -23,6 +23,9 @@ import (
 // not in settings.json: changing them needs no rebuild.
 type Prefs struct {
 	PingTargets []string `json:"pingTargets"`
+	// VLANs defined in the network page ("enp2s0.1001") that may not be used
+	// yet; the interface dropdowns offer them.
+	VLANs []string `json:"vlans,omitempty"`
 }
 
 var defaultPrefs = Prefs{PingTargets: []string{"gateway", "1.1.1.1", "9.9.9.9"}}
@@ -342,9 +345,6 @@ func (a *app) dashboardData(rangeName string) dashboard {
 	d.Charts = append(d.Charts, traffic("Internet ("+up+")", up))
 	for _, l := range f.LANs {
 		dev := l.Interface
-		if l.VLAN != "" {
-			dev += "." + l.VLAN
-		}
 		c := traffic("LAN "+l.Name+" ("+dev+")", dev)
 		// From the LAN's side: what the router sends is what the LAN downloads.
 		c.Lines[0].Label, c.Lines[1].Label = "to router", "from router"
@@ -395,7 +395,9 @@ func (a *app) dashboardFragment(w http.ResponseWriter, r *http.Request, sess ses
 func (a *app) savePrefs(w http.ResponseWriter, r *http.Request, sess session) {
 	targets, err := parsePingTargets(r.PostFormValue("pingTargets"))
 	if err == nil {
-		err = a.sys.savePrefs(Prefs{PingTargets: targets})
+		prefs := a.sys.loadPrefs()
+		prefs.PingTargets = targets
+		err = a.sys.savePrefs(prefs)
 	}
 	if err != nil {
 		http.Redirect(w, r, "/advanced?msg="+url.QueryEscape("Ping targets not saved: "+err.Error()), http.StatusSeeOther)