fix: iPad tablet toolbar styling and PR #34 refinements

- Scope toolbar bottom-offset to phone breakpoint only (position:fixed);
  prevents double-correction on iPad where toolbar is position:relative
- Extract keyboard accessory bar styles to top-level mobile.css so
  /init, /clear, /compact buttons render correctly on iPad
- Use desktop-style toolbar sizing on tablet (430-768px): smaller font,
  no forced min-height, proper gap between buttons
- Show voice/mic button on tablet (was hidden at <1023px with no
  mobile replacement above 430px)
- Bump CSS cache-bust version to 0.1633

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/web/public/index.html

@@ -9,8 +9,8 @@
   <link rel="manifest" href="manifest.json">
   <title>Codeman</title>
   <link rel="icon" type="image/svg+xml" href="data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 32 32'%3E%3Cdefs%3E%3ClinearGradient id='g' x1='0%25' y1='0%25' x2='100%25' y2='100%25'%3E%3Cstop offset='0%25' stop-color='%2360a5fa'/%3E%3Cstop offset='100%25' stop-color='%233b82f6'/%3E%3C/linearGradient%3E%3C/defs%3E%3Crect width='32' height='32' rx='6' fill='%230a0a0a'/%3E%3Cpath d='M18 4L8 18h6l-2 10 10-14h-6z' fill='url(%23g)'/%3E%3C/svg%3E">
-  <link rel="stylesheet" href="styles.css?v=0.1631">
-  <link rel="stylesheet" href="mobile.css?v=0.1631" media="(max-width: 1023px)">
+  <link rel="stylesheet" href="styles.css?v=0.1633">
+  <link rel="stylesheet" href="mobile.css?v=0.1633" media="(max-width: 1023px)">
   <!-- xterm.css loaded async — terminal won't display until xterm.js runs anyway -->
   <link rel="preload" href="vendor/xterm.css" as="style" onload="this.onload=null;this.rel='stylesheet'">
   <noscript><link rel="stylesheet" href="vendor/xterm.css"></noscript>