Restore shared code and add types

package.json

@@ -10,6 +10,7 @@
   "publishConfig": {
     "access": "public"
   },
+  "types": "src/main.d.ts",
   "main": "src/main.js",
   "exports": {
     ".": "./src/main.js",

src/main.d.ts

@@ -0,0 +1,14 @@
+declare module "@theme/Sandbox" {
+  interface Props {
+    codeMirror?: boolean;
+    height: string;
+    hideDevTools?: boolean;
+    id: string;
+    inline?: boolean;
+    previewWindow?: string;
+  }
+
+  export default function Sandbox(props: Props): JSX.Element;
+}
+
+export function buildUrl(id: string): string;

src/sandbox.js

@@ -0,0 +1,10 @@
+module.exports = {
+  buildUrl,
+};
+
+function buildUrl(id) {
+  const url = new URL("https://codesandbox.io/");
+  url.pathname = `/s/${id}`;
+
+  return url.toString();
+}