feat(next): migrate app to TypeScript, Vue 3, and Vite

- convert main/renderer/shared codebase from JS to TS - replace renderer pipeline with Vite using TS config - update all dependencies via pnpm and migrate lint/build configs - switch update/version checks to GitHub and add aria2 sync flow - add idle BT network guard toggle - clean legacy files and reorganize docs Hopefully patches: https://github.com/agalwood/Motrix/issues/1549 https://github.com/agalwood/Motrix/issues/831 https://github.com/agalwood/Motrix/issues/1798 https://github.com/agalwood/Motrix/issues/1698 https://github.com/agalwood/Motrix/issues/1728