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/LibraryScreen.tsx

@@ -192,12 +192,14 @@ export function LibraryScreen({ initialTab = "decks" }: { initialTab?: "decks" |
       {/* page header ---------------------------------------------------- */}
       <section className="mb-6 space-y-5">
         <div>
-          <h1 className="text-[24px] font-semibold leading-tight tracking-[-0.02em] text-[var(--text)] sm:text-[26px]">
-            {t("library.title")}
-          </h1>
-          <p className="mt-1.5 text-[13.5px] text-[var(--text-subtle)]">
-            {t("library.subtitle")}
-          </p>
+          <div className="page-heading">
+            <h1 className="text-[24px] font-semibold leading-tight tracking-[-0.02em] text-[var(--text)] sm:text-[26px]">
+              {t("library.title")}
+            </h1>
+            <p className="mt-1.5 text-[13.5px] text-[var(--text-subtle)]">
+              {t("library.subtitle")}
+            </p>
+          </div>
         </div>
 
         {/* Desktop keeps Import above the tabs; phones get a small icon
@@ -486,7 +488,7 @@ export function LibraryScreen({ initialTab = "decks" }: { initialTab?: "decks" |
 
                 {/* One quiet label replaces the redundant single-group heading. */}
                 {!hasFolders ? (
-                  <p className="mb-4 hidden text-[12px] font-medium text-[var(--text-subtle)] lg:block">
+                  <p className="hint-line mb-4 hidden text-[12px] font-medium text-[var(--text-subtle)] lg:block">
                     {t("common.allDecks")}
                   </p>
                 ) : null}