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/package.json

@@ -9,7 +9,8 @@
     "dev": "astro dev",
     "build": "astro build",
     "preview": "astro preview",
-    "astro": "astro"
+    "astro": "astro",
+    "indexnow:submit": "node ./scripts/submit-indexnow.mjs"
   },
   "dependencies": {
     "@astrojs/markdown-remark": "^7.0.1",
@@ -21,6 +22,7 @@
     "autoprefixer": "^10.4.27",
     "lucide-astro": "^0.556.0",
     "postcss": "^8.5.8",
+    "qrcode": "^1.5.4",
     "sharp": "^0.34.5",
     "svelte": "^5.55.0",
     "tailwindcss": "^3.4.19"