Navy theme from the app icon, frosted glass, and the new mark in-app

The icon's artwork is now the source of truth for the palette:

- frost-* is a navy-tinted neutral scale and accent-* is the icon's
  snowflake blue; light page #f4f7fd / sidebar #e9eff9 / border
  #dce4f1, dark page #0e1424 / sidebar #0a0f1c / surfaces #171f33.
- Surfaces are frosted glass: .card, .glass-panel, .list-group and
  .sidebar-surface are translucent with backdrop-blur/saturate, and the
  page wrapper no longer paints an opaque --page, so the fixed navy/blue
  backdrop reads through the sidebar, cards, chrome and sheets.
- The primary CTA is the icon's blue (#1d61ab in light, #59a8f7 in dark
  with ink text).
- The gate stage, fields and glows are navy/blue; viewport theme-color
  and the manifest background/theme colour are #0e1424.
- The old monochrome snowflake tile is gone from the brand: sidebar,
  header, key gate and empty state now show the real app icon (the
  install sheet already did). Decorative snowflakes stay.
- --surface-strong is finally defined (it was referenced but never
  declared, so those inputs had no fill).
- Icon URLs carry ?v=2 so browser favicon caches refetch.

Updated the contrast audit (21 pairs) and the deck-chrome token
assertions to the new theme. Verified: contrast 21/21, deck chrome
15/15, key gate 49/49, install sheet 64/64, final ux 12/12, retry
14/14, zoom 6/6, security 8/8, pwa 16/16, deck fixes 15/15.

app/create/page.tsx

@@ -11,7 +11,7 @@ export const metadata = {
 export default function CreatePage() {
   return (
     <ApiKeyGate>
-      <div className="flex min-h-dvh bg-[var(--page)]">
+      <div className="flex min-h-dvh">
         <Sidebar />
         <SidebarOffset />
         <MobileSidebar />