docs(course): add the 15-module web course and narrated editor video

Generate a static beginner course from course data with real Chromium
screenshots for every module, and record a narrated walkthrough of UV,
Texture Paint, Compositor, Geometry Nodes, Spreadsheet and OPFS reopen.
The render lesson video covers M08/M09; the course page is linked from
the tutorial landing.

Co-Authored-By: Claude Code <noreply@anthropic.com>

web/app/src/tutorial/TutorialLanding.tsx

@@ -38,7 +38,7 @@ export function TutorialLanding({ course }: { course: TutorialCourse }) {
   return <main className="parts-tutorial-landing" data-course={course.id}>
     <header className="parts-landing-top">
       <a className="parts-landing-brand" href="/" aria-label="返回 Web Blender"><span className="brand-mark" aria-hidden="true"><span className="brand-orbit" /></span><span>Blender Web</span></a>
-      <nav aria-label="教程导航"><a href="/manuals/WEB_Blender_Function_User_Guide.pdf" target="_blank" rel="noopener">使用手册</a>{course.lessonUrl ? <a href={course.lessonUrl} target="_blank" rel="noopener">渲染图文/视频教案</a> : null}<a href="/" className="parts-landing-return">直接打开 Blender</a></nav>
+      <nav aria-label="教程导航"><a href="/manuals/WEB_Blender_Function_User_Guide.pdf" target="_blank" rel="noopener">使用手册</a><a href="/tutorial/full/index.html" target="_blank" rel="noopener">全站入门课程</a>{course.lessonUrl ? <a href={course.lessonUrl} target="_blank" rel="noopener">渲染图文/视频教案</a> : null}<a href="/" className="parts-landing-return">直接打开 Blender</a></nav>
     </header>
     <section className="parts-landing-hero">
       <div>