feat(docs): add welcome screen with animated logo

Introduce a new welcome screen that automatically redirects first-time visitors from the homepage. The screen features an animated "Easy Vibe" logo with three color themes (ocean, rainbow, sunset) that cycle through a drawing animation. Users can click anywhere to enter the main site.

The welcome screen includes:
- A JSON file containing SVG path data for the animated logo
- A Vue component with gradient backgrounds and smooth animations
- Logic to detect first-time visitors using localStorage
- Integration into the existing VitePress theme structure
- Updated navigation to exclude the welcome page from sidebar controls
- Modified homepage logic to redirect to welcome screen on first visit

docs/public/sitemap.xml

@@ -772,7 +772,7 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-0/0.1-learning-map/</loc>
-    <lastmod>2026-02-26T04:35:28+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-0/0.1-learning-map/"/>
@@ -780,7 +780,7 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-0/0.2-ai-capabilities-through-games/</loc>
-    <lastmod>2026-02-26T04:35:28+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-0/0.2-ai-capabilities-through-games/"/>
@@ -812,7 +812,7 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.1-introduction-to-ai-ide/</loc>
-    <lastmod>2026-03-06T17:59:01+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.1-introduction-to-ai-ide/"/>
@@ -820,7 +820,7 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.2-building-prototype/</loc>
-    <lastmod>2026-03-06T17:59:01+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.2-building-prototype/"/>
@@ -828,7 +828,7 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.3-integrating-ai-capabilities/</loc>
-    <lastmod>2026-03-12T13:45:38+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.3-integrating-ai-capabilities/"/>
@@ -836,7 +836,7 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.4-complete-project-practice/</loc>
-    <lastmod>2026-02-26T05:34:19+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.9</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-1/1.4-complete-project-practice/"/>
@@ -963,14 +963,14 @@
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-2/frontend/2.0-lovart-assets/</loc>
-    <lastmod>2026-03-05T22:32:03+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.8</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-2/frontend/2.0-lovart-assets/"/>
   </url>
   <url>
     <loc>https://datawhalechina.github.io/easy-vibe/zh-cn/stage-2/frontend/2.1-figma-mastergo/</loc>
-    <lastmod>2026-02-27T18:46:11+08:00</lastmod>
+    <lastmod>2026-03-16T12:42:29+08:00</lastmod>
     <changefreq>weekly</changefreq>
     <priority>0.8</priority>
     <xhtml:link rel="alternate" hreflang="zh-CN" href="https://datawhalechina.github.io/easy-vibe/zh-cn/stage-2/frontend/2.1-figma-mastergo/"/>