feat(ui): rebuild homepage with new sections and i18n

This commit introduces a complete overhaul of the homepage, rebuilding it from the ground up with Nuxt UI and full
internationalization support. The new design better showcases the studio's capabilities and projects.

- Re-architected the index page with multiple new sections: Capabilities, Featured Projects, Tech Stack, and Why Choose Us.
- Implemented full i18n for English (en-US) and Chinese (zh-CN) across all new content.
- Centralized the page structure into a `default.vue` layout with a global header (including color mode and locale selectors) and
footer.
- Replaced placeholder logos with a dynamic `UMarquee` of technology icons using Iconify.

package.json

@@ -10,6 +10,7 @@
     "postinstall": "nuxt prepare"
   },
   "dependencies": {
+    "@iconify-json/mdi": "^1.2.3",
     "@nuxt/content": "3.8.0",
     "@nuxt/eslint": "1.10.0",
     "@nuxt/ui": "4.1.0",