feat: initialize markr nostr bookmark client

- Add project structure with TypeScript, React, and Vite
- Implement nostr authentication using browser extension (NIP-07)
- Add NIP-51 compliant bookmark fetching and display
- Create minimal UI with login and bookmark components
- Integrate applesauce-core and applesauce-react libraries
- Add responsive styling with dark/light mode support
- Include comprehensive README with setup instructions

This is a minimal MVP for a nostr bookmark client that allows users to
view their bookmarks according to NIP-51 specification.

node_modules/vfile/lib/minurl.shared.js

@@ -0,0 +1,31 @@
+/**
+ * Checks if a value has the shape of a WHATWG URL object.
+ *
+ * Using a symbol or instanceof would not be able to recognize URL objects
+ * coming from other implementations (e.g. in Electron), so instead we are
+ * checking some well known properties for a lack of a better test.
+ *
+ * We use `href` and `protocol` as they are the only properties that are
+ * easy to retrieve and calculate due to the lazy nature of the getters.
+ *
+ * We check for auth attribute to distinguish legacy url instance with
+ * WHATWG URL instance.
+ *
+ * @param {unknown} fileUrlOrPath
+ *   File path or URL.
+ * @returns {fileUrlOrPath is URL}
+ *   Whether it’s a URL.
+ */
+// From: <https://github.com/nodejs/node/blob/6a3403c/lib/internal/url.js#L720>
+export function isUrl(fileUrlOrPath) {
+  return Boolean(
+    fileUrlOrPath !== null &&
+      typeof fileUrlOrPath === 'object' &&
+      'href' in fileUrlOrPath &&
+      fileUrlOrPath.href &&
+      'protocol' in fileUrlOrPath &&
+      fileUrlOrPath.protocol &&
+      // @ts-expect-error: indexing is fine.
+      fileUrlOrPath.auth === undefined
+  )
+}