feat: add SharePanel component for social sharing with QR code support

- Implemented SharePanel component in `SharePanel.astro` for sharing content on social media platforms.
- Integrated QR code generation for WeChat sharing using the `qrcode` library.
- Added localization support for English and Chinese languages.
- Created utility functions in `seo.ts` for building article summaries and FAQs.
- Introduced API routes for serving IndexNow key and generating full LLM catalog and summaries.
- Enhanced SEO capabilities with structured data for articles and pages.

frontend/src/lib/api/client.ts

@@ -294,6 +294,7 @@ export interface ApiSiteSettings {
   subscription_popup_delay_seconds: number | null;
   seo_default_og_image: string | null;
   seo_default_twitter_handle: string | null;
+  seo_wechat_share_qr_enabled: boolean;
 }
 
 export interface ContentAnalyticsInput {
@@ -491,6 +492,7 @@ export const DEFAULT_SITE_SETTINGS: SiteSettings = {
   seo: {
     defaultOgImage: undefined,
     defaultTwitterHandle: undefined,
+    wechatShareQrEnabled: false,
   },
 };
 
@@ -509,6 +511,8 @@ const normalizePost = (post: ApiPost): UiPost => ({
   description: post.description,
   content: post.content,
   date: formatPostDate(post.created_at),
+  createdAt: post.created_at,
+  updatedAt: post.updated_at,
   readTime: estimateReadTime(post.content || post.description),
   type: post.post_type,
   tags: post.tags ?? [],
@@ -662,6 +666,7 @@ const normalizeSiteSettings = (settings: ApiSiteSettings): SiteSettings => {
   seo: {
     defaultOgImage: settings.seo_default_og_image ?? undefined,
     defaultTwitterHandle: settings.seo_default_twitter_handle ?? undefined,
+    wechatShareQrEnabled: Boolean(settings.seo_wechat_share_qr_enabled),
   },
   };
 };