Added lefthook to enforce no non-type export in src/@types

.dependency-cruiser.cjs

@@ -1,6 +1,18 @@
 /** @type {import('dependency-cruiser').IConfiguration} */
 module.exports = {
   forbidden: [
+    {
+      name: "no-non-type-@type-exports",
+      severity: "error",
+      comment:
+        "Files in @types should not export anything but types and interfaces. " +
+        "The folder is intended to house imports that are removed at runtime, " +
+        "and thus should not contain anything with a bearing on runtime code.",
+      to: {
+        path: "(^|/)src/@types",
+        dependencyTypesNot: ["type-only"],
+      },
+    },
     {
       name: "only-type-imports",
       severity: "error",