checker: split monolithic rule into per-concern rules

checker/rules_zone.go

@@ -0,0 +1,13 @@
+package checker
+
+import sdk "git.happydns.org/checker-sdk-go/checker"
+
+// zoneRule covers Zonemaster's zone test module (SOA values, MX presence,
+// mandatory records at the apex).
+func zoneRule() sdk.CheckRule {
+	return &categoryRule{
+		name:        "zonemaster.zone",
+		description: "Zonemaster zone tests (SOA values, MX presence, mandatory records).",
+		modules:     []string{"zone"},
+	}
+}