move shim to new package

packages/shim/src/url.js

@@ -0,0 +1,24 @@
+export const urlShim = {
+  URL: globalThis.URL,
+  URLSearchParams: globalThis.URLSearchParams,
+
+  pathToFileURL(p) {
+    // Return an object with .href matching Node's url.pathToFileURL behavior
+    const encoded = encodeURI(p.replace(/\\/g, "/"));
+    const href = "file:///" + encoded.replace(/^\/+/, "");
+
+    return { href, toString: () => href };
+  },
+
+  fileURLToPath(url) {
+    let str = typeof url === "string" ? url : url.href || url.toString();
+
+    if (str.startsWith("file:///")) {
+      str = str.slice(8);
+    } else if (str.startsWith("file://")) {
+      str = str.slice(7);
+    }
+
+    return decodeURI(str);
+  },
+};