feat(pages): add web development services page

This commit introduces a new page at `/webDev` to display web development services and pricing plans.

To support this, a new reusable composable `useLocalizedCollection` has been created to simplify fetching localized content from Nuxt
Content. The index page has been refactored to use this new composable.

- Adds `webDev.vue` page and corresponding `webDev.yml` content files for EN and ZH.
- Defines a Zod schema in `content.config.ts` for the new content type.
- Updates the navigation link to point to the new page.

app/composables/LocalizedCollection.ts

@@ -0,0 +1,66 @@
+// /composables/useLocalizedCollection.ts
+import type { Collections } from "@nuxt/content";
+
+export type UseLocalizedOptions = {
+  /** 默认 locale -> suffix 映射 */
+  localeMap?: Record<string, string>;
+  /** 回退 locale 的 suffix（例如 'en'） */
+  fallbackSuffix?: string;
+  /** 当找不到内容时是否抛错，默认 true */
+  throwOnMissing?: boolean;
+  /** useAsyncData 的 key 前缀（默认等于 baseName） */
+  keyPrefix?: string;
+};
+
+function asCollectionKey(key: string) {
+  return key as keyof Collections;
+}
+
+/**
+ * 带类型安全的多语言内容加载器
+ * @example
+ * const { data: page } = await useLocalizedCollection('index')
+ */
+export function useLocalizedCollection<
+  B extends string, // 基础名称
+>(baseName: B, opts: UseLocalizedOptions = {}) {
+  const { locale } = useI18n();
+
+  const localeMap = opts.localeMap ?? { en: "en", "zh-CN": "zh" };
+  const fallbackSuffix = opts.fallbackSuffix ?? "en";
+  const keyPrefix = opts.keyPrefix ?? baseName;
+  const throwOnMissing = opts.throwOnMissing ?? true;
+
+  // 🔥 自动推断对应集合类型
+  type LocalizedKey = keyof {
+    [K in keyof Collections as K extends `${B}_${string}` ? K : never]: any;
+  };
+  type Schema = Collections[LocalizedKey];
+
+  return useAsyncData<Schema | null>(
+    `${keyPrefix}-${locale.value}`,
+    async () => {
+      const suffix =
+        localeMap[locale.value] ?? locale.value.split("-")[0] ?? "en";
+      const key = asCollectionKey(`${baseName}_${suffix}`);
+      let content = (await queryCollection(key).first()) as Schema | null;
+
+      if (!content && suffix !== fallbackSuffix) {
+        const fallbackKey = asCollectionKey(`${baseName}_${fallbackSuffix}`);
+        content = (await queryCollection(fallbackKey).first()) as Schema | null;
+      }
+
+      return content;
+    },
+    { watch: [locale] }
+  ).then((res) => {
+    if (throwOnMissing && res && !res.data?.value) {
+      throw createError({
+        statusCode: 404,
+        statusMessage: `Page not found: ${baseName} for locale ${locale.value}`,
+        fatal: true,
+      });
+    }
+    return res;
+  });
+}