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-normalize-identifier/index.js

@@ -0,0 +1,33 @@
+/**
+ * Normalize an identifier (as found in references, definitions).
+ *
+ * Collapses markdown whitespace, trim, and then lower- and uppercase.
+ *
+ * Some characters are considered “uppercase”, such as U+03F4 (`ϴ`), but if their
+ * lowercase counterpart (U+03B8 (`θ`)) is uppercased will result in a different
+ * uppercase character (U+0398 (`Θ`)).
+ * So, to get a canonical form, we perform both lower- and uppercase.
+ *
+ * Using uppercase last makes sure keys will never interact with default
+ * prototypal values (such as `constructor`): nothing in the prototype of
+ * `Object` is uppercase.
+ *
+ * @param {string} value
+ *   Identifier to normalize.
+ * @returns {string}
+ *   Normalized identifier.
+ */
+export function normalizeIdentifier(value) {
+  return value
+  // Collapse markdown whitespace.
+  .replace(/[\t\n\r ]+/g, " ")
+  // Trim.
+  .replace(/^ | $/g, '')
+  // Some characters are considered “uppercase”, but if their lowercase
+  // counterpart is uppercased will result in a different uppercase
+  // character.
+  // Hence, to get that form, we perform both lower- and uppercase.
+  // Upper case makes sure keys will not interact with default prototypal
+  // methods: no method is uppercase.
+  .toLowerCase().toUpperCase();
+}