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/mac-dictation/index.html

@@ -5,11 +5,11 @@
   <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/">
-  <meta http-equiv="refresh" content="0; url=../">
-  <script>location.replace("../");</script>
+  <link rel="canonical" href="https://osg.osglab.com/#platforms">
+  <meta http-equiv="refresh" content="0; url=../#platforms">
+  <script>location.replace("../#platforms");</script>
 </head>
 <body>
-  <p><a href="../">OSGKeyboard</a></p>
+  <p><a href="../#platforms">OSGKeyboard — Mac 语音输入</a></p>
 </body>
 </html>