site: Add official website source

- Set VitePress base to '/docs/' for serving documentation at /docs/ route
- Update favicon path in head config to '/docs/favicon.ico'
- Add build:site script to build website and docs, then merge outputs

website/public/_redirects

@@ -0,0 +1,2 @@
+/docs/*  /docs/:splat  200
+/*       /index.html   200

website/public/robots.txt

@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://hapi.manus.space/sitemap.xml

website/public/sitemap.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:xhtml="http://www.w3.org/1999/xhtml">
+  <url>
+    <loc>https://hapi.manus.space/</loc>
+    <lastmod>2025-01-01</lastmod>
+    <changefreq>weekly</changefreq>
+    <priority>1.0</priority>
+    <xhtml:link rel="alternate" hreflang="en" href="https://hapi.manus.space/?lng=en"/>
+    <xhtml:link rel="alternate" hreflang="zh" href="https://hapi.manus.space/?lng=zh"/>
+  </url>
+</urlset>