chore: upgrade tooling stack

- 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

.prettierrc

@@ -1,5 +1,9 @@
 {
   "semi": false,
   "singleQuote": true,
+  "tabWidth": 2,
+  "trailingComma": "none",
+  "printWidth": 80,
+  "endOfLine": "lf",
   "arrowParens": "always"
 }