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/mdast-util-to-markdown/lib/configure.js

@@ -0,0 +1,79 @@
+/**
+ * @import {Options, State} from './types.js'
+ */
+
+const own = {}.hasOwnProperty
+
+/**
+ * @param {State} base
+ * @param {Options} extension
+ * @returns {State}
+ */
+export function configure(base, extension) {
+  let index = -1
+  /** @type {keyof Options} */
+  let key
+
+  // First do subextensions.
+  if (extension.extensions) {
+    while (++index < extension.extensions.length) {
+      configure(base, extension.extensions[index])
+    }
+  }
+
+  for (key in extension) {
+    if (own.call(extension, key)) {
+      switch (key) {
+        case 'extensions': {
+          // Empty.
+          break
+        }
+
+        /* c8 ignore next 4 */
+        case 'unsafe': {
+          list(base[key], extension[key])
+          break
+        }
+
+        case 'join': {
+          list(base[key], extension[key])
+          break
+        }
+
+        case 'handlers': {
+          map(base[key], extension[key])
+          break
+        }
+
+        default: {
+          // @ts-expect-error: matches.
+          base.options[key] = extension[key]
+        }
+      }
+    }
+  }
+
+  return base
+}
+
+/**
+ * @template T
+ * @param {Array<T>} left
+ * @param {Array<T> | null | undefined} right
+ */
+function list(left, right) {
+  if (right) {
+    left.push(...right)
+  }
+}
+
+/**
+ * @template T
+ * @param {Record<string, T>} left
+ * @param {Record<string, T> | null | undefined} right
+ */
+function map(left, right) {
+  if (right) {
+    Object.assign(left, right)
+  }
+}