docs(pages): redesign homepage motion and target voice-keyboard SEO keywords

- Move all canonical, hreflang, Open Graph, sitemap, robots, and llms.txt
  URLs to the custom domain https://osg.osglab.com/
- Put category keywords (AI 语音输入法, 嘴替输入法, Agentic keyboard) in
  the title, description, H1, section eyebrows, FAQ, and JSON-LD
- Add a 1200x630 social card and large-image Twitter card
- Add a scroll-driven three-act story (dictation, reply in your voice,
  agentic action), a live voice capsule, split-text headings, number
  counters, parallax media reveals, pointer spotlight and tilt, and a
  circular theme transition
- Keep the page fully readable without JavaScript and under reduced motion
- Point legacy redirect pages at sections that exist

docs/en/index.html

@@ -5,7 +5,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>Redirecting · OSGKeyboard</title>
   <meta name="robots" content="noindex">
-  <link rel="canonical" href="https://hkgood.github.io/OSGKeyboard/?lang=en">
+  <link rel="canonical" href="https://osg.osglab.com/?lang=en">
   <meta http-equiv="refresh" content="0; url=../?lang=en">
   <script>location.replace("../?lang=en");</script>
 </head>