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/micromark-util-decode-string/index.js

@@ -0,0 +1,45 @@
+import { decodeNamedCharacterReference } from 'decode-named-character-reference';
+import { decodeNumericCharacterReference } from 'micromark-util-decode-numeric-character-reference';
+const characterEscapeOrReference = /\\([!-/:-@[-`{-~])|&(#(?:\d{1,7}|x[\da-f]{1,6})|[\da-z]{1,31});/gi;
+
+/**
+ * Decode markdown strings (which occur in places such as fenced code info
+ * strings, destinations, labels, and titles).
+ *
+ * The “string” content type allows character escapes and -references.
+ * This decodes those.
+ *
+ * @param {string} value
+ *   Value to decode.
+ * @returns {string}
+ *   Decoded value.
+ */
+export function decodeString(value) {
+  return value.replace(characterEscapeOrReference, decode);
+}
+
+/**
+ * @param {string} $0
+ *   Match.
+ * @param {string} $1
+ *   Character escape.
+ * @param {string} $2
+ *   Character reference.
+ * @returns {string}
+ *   Decoded value
+ */
+function decode($0, $1, $2) {
+  if ($1) {
+    // Escape.
+    return $1;
+  }
+
+  // Reference.
+  const head = $2.charCodeAt(0);
+  if (head === 35) {
+    const head = $2.charCodeAt(1);
+    const hex = head === 120 || head === 88;
+    return decodeNumericCharacterReference($2.slice(hex ? 2 : 1), hex ? 16 : 10);
+  }
+  return decodeNamedCharacterReference($2) || $0;
+}