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/robots.txt

@@ -23,4 +23,4 @@ Allow: /
 User-agent: Bytespider
 Allow: /
 
-Sitemap: https://hkgood.github.io/OSGKeyboard/sitemap.xml
+Sitemap: https://osg.osglab.com/sitemap.xml