feat(docs): add NavGrid/NavCard components and restructure stage pages

- Add NavGrid.vue and NavCard.vue components for better navigation layout
- Restructure stage-0 index pages across languages into intro.md with new navigation components
- Remove old stage-0 index.md files and update stage-3 pages similarly
- Add new dependencies 'claude' and 'codex' to package.json
- Improve code formatting in multiple Vue components for better readability
- Update documentation content and structure for better user experience

docs/.vitepress/theme/Layout.vue

@@ -195,7 +195,10 @@ watch(lineHeight, (next) => {
     </template>
     <template #home-hero-info-after>
       <div
-        v-if="frontmatter.layout === 'home' && (frontmatter.hero?.tagline || frontmatter.hero?.typingTagline)"
+        v-if="
+          frontmatter.layout === 'home' &&
+          (frontmatter.hero?.tagline || frontmatter.hero?.typingTagline)
+        "
         class="vp-typed-tagline"
       >
         <ClientOnly>