Remove the toolchain image module; node-tools is the repository's only module (issue 979, S1; ADR 0524 §5)

Only build-agent built inside that image, and it goes in R4g.

node-tools/internal/meshtest/meshtest_test.go

@@ -90,3 +90,32 @@ func TestBundlesCannotBeLaunchedWithoutNodeOrTheSDKAndTheSkipSaysWhy(t *testing.
 		t.Errorf("node and the package present said %q", why)
 	}
 }
+
+// The checker runs node-tools' Go level by Go's convention and its Node level by package.json's test script
+// (novox/hq ADR 0529): no script of the repository's own runs beside them, and no module but node-tools is built from
+// here (ADR 0524 §5, the toolchain image retired).
+func TestTheRepositoryHoldsNoCheckScriptAndNodeToolsIsItsOnlyModule(t *testing.T) {
+	root := filepath.Join("..", "..", "..")
+	if _, err := os.Stat(filepath.Join(root, "merge-check.sh")); err == nil {
+		t.Errorf("merge-check.sh is back: the checker's levels run the tests")
+	}
+	var found []string
+	err := filepath.WalkDir(root, func(p string, d os.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+		if d.IsDir() && (d.Name() == "node_modules" || d.Name() == ".git") {
+			return filepath.SkipDir
+		}
+		if !d.IsDir() && d.Name() == "module.json" {
+			found = append(found, filepath.ToSlash(p))
+		}
+		return nil
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(found) != 1 || !strings.HasSuffix(found[0], "/node-tools/module.json") {
+		t.Errorf("the module manifests are %v, want node-tools' alone", found)
+	}
+}