refactor(content): migrate index page to Nuxt Content

This commit refactors the index page to source its content from @nuxt/content, replacing the previous implementation that used i18n
JSON files and hardcoded data within the component.

Key changes:
- Introduced `content.config.ts` to define collections and Zod schemas for type-safe content.
- Moved page content into localized YAML files (`content/en-US/index.yml` and `content/zh-CN/index.yml`).
- Updated `app/pages/index.vue` to fetch data dynamically using `useAsyncData` and `queryCollection`.
- Removed redundant content from i18n JSON files and the Vue component script.

This change decouples content from presentation, improves maintainability, and centralizes content management.

content.config.ts

@@ -0,0 +1,86 @@
+import { defineContentConfig, defineCollection, z } from "@nuxt/content";
+
+export default defineContentConfig({
+  collections: {
+    index_en: defineCollection({
+      type: "page",
+      source: "en-US/index.yml",
+      schema: z.object({
+        capabilities: z.object({
+          title: z.string(),
+          features: z.array(
+            z.object({
+              title: z.string(),
+              description: z.string(),
+              icon: z.string(),
+            })
+          ),
+        }),
+        featuredProjects: z.object({
+          title: z.string(),
+          projects: z.array(
+            z.object({
+              title: z.string(),
+              description: z.string(),
+              image: z.string(),
+              demoLink: z.string(),
+            })
+          ),
+        }),
+        techStack: z.object({
+          title: z.string(),
+        }),
+        whyChooseUs: z.object({
+          title: z.string(),
+          features: z.array(
+            z.object({
+              title: z.string(),
+              description: z.string(),
+              icon: z.string(),
+            })
+          ),
+        }),
+      }),
+    }),
+    index_zh: defineCollection({
+      type: "page",
+      source: "zh-CN/index.yml",
+      schema: z.object({
+        capabilities: z.object({
+          title: z.string(),
+          features: z.array(
+            z.object({
+              title: z.string(),
+              description: z.string(),
+              icon: z.string(),
+            })
+          ),
+        }),
+        featuredProjects: z.object({
+          title: z.string(),
+          projects: z.array(
+            z.object({
+              title: z.string(),
+              description: z.string(),
+              image: z.string(),
+              demoLink: z.string(),
+            })
+          ),
+        }),
+        techStack: z.object({
+          title: z.string(),
+        }),
+        whyChooseUs: z.object({
+          title: z.string(),
+          features: z.array(
+            z.object({
+              title: z.string(),
+              description: z.string(),
+              icon: z.string(),
+            })
+          ),
+        }),
+      }),
+    }),
+  },
+});