perf(ui/sidebar): optimize setup process and i18n lazy load

[qwqcode]

Referring to the example provided by vue-i18n for dynamically importing locale resources in Vite, we made modifications to the sidebar of artalk. We split different languages into separate locale files and load the corresponding language files using lazy loading.

Additionally, we made changes to the sidebar initialization process and its interaction with the core artalk program. The process is now clearer, but further optimization is still needed.

References:

• https://github.com/intlify/vue-i18n/tree/8eb10cd05f181fb9bbf5e07603e6aa35c79245b0/examples/lazy-loading/vite
• https://vitejs.dev/guide/features#dynamic-import