Disable records instead of deleting them

A disabled record stays in Jarl with its ID, TTL and comment but is
left out of the zone; the zone file lists it as a comment. Web UI
toggle, jarl record disable|enable, record.disable|enable operations
and API endpoints. Database schema 5.

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

internal/server/h_nscheck.go

@@ -169,7 +169,7 @@ func (s *Server) zoneDelegation(w http.ResponseWriter, r *http.Request, p *auth.
 		c.Resolver = net.JoinHostPort(a.String(), "53")
 	}
 	var ns []string
-	for _, rec := range st.ZoneRecords(z.ID) {
+	for _, rec := range st.ServedRecords(z.ID) {
 		if rec.Type == "NS" && rec.Name == z.Name {
 			ns = append(ns, rec.Data)
 		}
@@ -226,7 +226,7 @@ func (s *Server) localSerial(ctx context.Context, st *model.State, z *model.Zone
 // addresses Jarl has for them in the same view (or nil, to be looked up).
 func nsTargets(st *model.State, z *model.Zone) []nscheck.Target {
 	var out []nscheck.Target
-	for _, rec := range st.ZoneRecords(z.ID) {
+	for _, rec := range st.ServedRecords(z.ID) {
 		if rec.Type != "NS" || rec.Name != z.Name {
 			continue
 		}
@@ -244,7 +244,7 @@ func jarlAddresses(st *model.State, viewID int64, name string) []string {
 		if !z.HasRecords() || !dnsname.IsSubdomain(name, z.Name) {
 			continue
 		}
-		for _, rec := range st.ZoneRecords(z.ID) {
+		for _, rec := range st.ServedRecords(z.ID) {
 			if rec.Name == name && (rec.Type == "A" || rec.Type == "AAAA") {
 				out = append(out, rec.Data)
 			}