Design pass (all themes + chat UI), model picker, reduce-motion toggle

- Aero: blue gradients back on the active segment and every primary
  (Review due, the card's Study button, the composer's send button); a
  frosted backing behind the page heading and the All decks label; a
  bottom-weighted rail tint; chat header/composer/welcome panels; calmer
  orbs; stronger card veil + a stronger blur bake.
- Dark/Light: a dedicated --track token makes progress bars read (the
  first attempt shifted --surface-sunken and the pixel scan caught the
  sheet-contrast regression); brighter dark secondary text; darker light
  segmented labels and difficulty tints; stronger light card border and
  shadow.
- Chat UI: friendly model chip ("Gemma 4 31B") with the raw name in a
  tooltip, larger chips, plain centered disclaimer, vertically centered
  welcome panel, distinct chat-plus icon for new chat.
- Chat models: every chat-capable model from the server's /api/tags is
  selectable (favourites first, search field when long, live-list
  validation in the route); default CHAT_MODEL_DEFAULT or gemma4:31b.
- Reduce motion: Settings toggle (default off) that parks the scene,
  collapses CSS animations and drives framer-motion's calm mode.
- Folders hint, "New" badge on fresh decks.

Contrast: 0 findings, axe clean, mobile 126/126, chat 102/102, wizard
95/95, regression 44/44, i18n 13/13, native 33/33.
Version 0.4.6, SW -> freezmo-v71.

components/chat/ContextPicker.tsx

@@ -107,7 +107,7 @@ export function ContextPicker({
         "flex w-full items-center gap-3 rounded-2xl border px-3 py-3 text-left transition",
         scope.kind === value
           ? "border-[var(--nav-active-border)] bg-[var(--nav-active-bg)]"
-          : "border-[var(--hairline-soft)] bg-[var(--surface-bg)] hover:bg-[var(--hover)]",
+          : "border-[var(--hairline-soft)] bg-[var(--surface-strong)] hover:bg-[var(--hover)]",
       )}
     >
       <span className="shrink-0 text-[var(--text-muted)]">{icon}</span>