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/eslint/lib/shared/string-utils.js

@@ -0,0 +1,60 @@
+/**
+ * @fileoverview Utilities to operate on strings.
+ * @author Stephen Wade
+ */
+
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const Graphemer = require("graphemer").default;
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+// eslint-disable-next-line no-control-regex -- intentionally including control characters
+const ASCII_REGEX = /^[\u0000-\u007f]*$/u;
+
+/** @type {Graphemer | undefined} */
+let splitter;
+
+//------------------------------------------------------------------------------
+// Public Interface
+//------------------------------------------------------------------------------
+
+/**
+ * Converts the first letter of a string to uppercase.
+ * @param {string} string The string to operate on
+ * @returns {string} The converted string
+ */
+function upperCaseFirst(string) {
+    if (string.length <= 1) {
+        return string.toUpperCase();
+    }
+    return string[0].toUpperCase() + string.slice(1);
+}
+
+/**
+ * Counts graphemes in a given string.
+ * @param {string} value A string to count graphemes.
+ * @returns {number} The number of graphemes in `value`.
+ */
+function getGraphemeCount(value) {
+    if (ASCII_REGEX.test(value)) {
+        return value.length;
+    }
+
+    if (!splitter) {
+        splitter = new Graphemer();
+    }
+
+    return splitter.countGraphemes(value);
+}
+
+module.exports = {
+    upperCaseFirst,
+    getGraphemeCount
+};