- TypeScript 3.9 -> 5.8 - ESLint 6 -> 9 (flat config) - Prettier 1 -> 3 - eslint-plugin-vue 6 -> 9 - Add vue-tsc for type checking - Migrate Sass @import to @use syntax - Fix Pinia persistence config for v4 - Add Spotify type declarations - Remove unused registerServiceWorker.ts