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/privacy/index.html

@@ -6,11 +6,11 @@
   <title>Privacy Policy · OSGKeyboard</title>
   <meta name="description" content="OSGKeyboard privacy policy: no account required for core use, on-device speech recognition by default, optional user-configured or managed cloud services, limited first-party analytics with opt-out, no sale of personal data.">
   <meta name="robots" content="index, follow">
-  <link rel="canonical" href="https://hkgood.github.io/OSGKeyboard/privacy/">
+  <link rel="canonical" href="https://osg.osglab.com/privacy/">
   <link rel="icon" href="../assets/app-icon.png" type="image/png">
   <meta property="og:title" content="OSGKeyboard Privacy Policy">
   <meta property="og:description" content="No account required for core use. On-device by default, with optional user-configured or managed cloud services.">
-  <meta property="og:url" content="https://hkgood.github.io/OSGKeyboard/privacy/">
+  <meta property="og:url" content="https://osg.osglab.com/privacy/">
   <meta property="og:type" content="website">
   <style>
     :root { color-scheme: light dark; --bg: #f7faf8; --ink: #102218; --muted: #5c6c62; --line: rgba(16, 34, 24, 0.12); --green: #238b48; }