Add UI editing for local DNS zones

Local zones were only editable as mounted files, so operators could not manage DNS entries from the console. Add a Local zones editor backed by a shared Kubernetes ConfigMap, validate master files before saving, scope the pod service account to that ConfigMap, and reload changed zones on every replica while flushing stale cache entries.

internal/zonefile/zonefile.go

@@ -577,13 +577,20 @@ func ParseFiles(paths []string, originFor func(string) string) (*Zone, error) {
 	return z, nil
 }
 
-// OriginFromPath derives a zone origin from a file path: "rpz/ads.zone" and
-// "ads.zone" both become "ads.zone.".
+// OriginFromPath derives a zone origin from a file path. Legacy names such as
+// "rpz/ads.zone" and "ads.zone" become "ads."; UI-managed names use the
+// "zone--" marker so "zone--example.com.zone" becomes "example.com.".
 func OriginFromPath(p string) string {
 	base := p
 	if i := strings.LastIndexByte(base, '/'); i >= 0 {
 		base = base[i+1:]
 	}
+	// The UI stores fully-qualified zone names with a marker so they do not
+	// collide with the legacy filename convention where "local.example.zone"
+	// means the "local." zone.
+	if strings.HasPrefix(base, "zone--") && strings.HasSuffix(base, ".zone") {
+		return ensureDot(strings.TrimSuffix(strings.TrimPrefix(base, "zone--"), ".zone"))
+	}
 	if i := strings.IndexByte(base, '.'); i > 0 {
 		base = base[:i]
 	}