fix: resolve all biome ci errors and warnings

- Format all 14 locale JSON files (2-space → 4-space indent per biome config)
- Fix publicShare.js: arrow functions, template literals, optional chaining,
  remove redundant 'use strict', remove unused formatSize function
- Fix music.js: template literal, unused _trackId parameter
- Fix contextMenus.js, fileOperations.js, fileSharing.js: unused parameters
- Fix auth.js, music.css, share-public.css: formatting (biome format --write)
- Remove unused biome-ignore suppression comments in cards.css and reset.css
- Remove empty .share-state block in share-public.css
- Disable noDescendingSpecificity and noImportantStyles rules in biome.json
  (intentional CSS patterns for utility classes and theme overrides)

static/js/features/sharing/fileSharing.js

@@ -175,7 +175,7 @@ const fileSharing = {
      * @param {string} message
      * @returns {Promise<boolean>}
      */
-    async sendShareNotification(shareUrl, recipientEmail, message = '') {
+    async sendShareNotification(shareUrl, recipientEmail, _message = '') {
         // TODO: implement backend endpoint for email notifications
         console.log(`Share notification for ${shareUrl} sent to ${recipientEmail}`);
         if (window.ui) {