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/util/check-rule-repetition.js

@@ -0,0 +1,21 @@
+/**
+ * @import {Options, State} from 'mdast-util-to-markdown'
+ */
+
+/**
+ * @param {State} state
+ * @returns {Exclude<Options['ruleRepetition'], null | undefined>}
+ */
+export function checkRuleRepetition(state) {
+  const repetition = state.options.ruleRepetition || 3
+
+  if (repetition < 3) {
+    throw new Error(
+      'Cannot serialize rules with repetition `' +
+        repetition +
+        '` for `options.ruleRepetition`, expected `3` or more'
+    )
+  }
+
+  return repetition
+}