tools(skills): add encrypted-dns-skill (ednsdiag CLI + agent skill)

.agents/skills/encrypted-dns-skill/internal/edns/providers_test.go

@@ -0,0 +1,18 @@
+package edns
+
+import "testing"
+
+func TestBuiltInProvidersHaveStrictEndpoints(t *testing.T) {
+	for _, name := range []string{"cloudflare", "google", "quad9", "adguard"} {
+		provider, err := FindProvider(name)
+		if err != nil {
+			t.Fatalf("find provider %s: %v", name, err)
+		}
+		if provider.DoHURL == "" || provider.DoTAddr == "" || provider.DoTName == "" {
+			t.Fatalf("provider %s is incomplete: %#v", name, provider)
+		}
+	}
+	if _, err := FindProvider("custom"); err == nil {
+		t.Fatal("unapproved custom provider was accepted")
+	}
+}