feat(design): the field family, the dropdown trigger, native controls, the no-raw-input lint rule (E28 S3c)

- ui/Input, Textarea, InnerInput + fieldClass (A4): the >= 3:1 edge, a 2px accent
  focus edge, the danger edge for invalid, md/sm/xs/heading rungs, 1rem and 44 on touch
- ui/SelectTrigger (A5): SortControl, FilterSelect, the view switcher and the date
  filter on one trigger, a pill in a toolbar, r8 in a form
- ui/NativeControls (A6): Checkbox, CheckRow, Slider, ColorInput
- every raw input swept (~100 sites); inputCls retired; local/input-primitive
- useReturnFocus: an in-place editor hands the focus back to its trigger on
  Enter/Escape (the playlist and Plex title renames, the priority number);
  the Plex playlist rename gains Escape and an accessible name
- back to top: a round 48 FAB (owner decision); DESIGN.md A2 and the log

frontend/src/components/PlexPlaylistView.tsx

@@ -41,6 +41,8 @@ import {
   useSortableA11y,
   useSortableItem,
 } from "./ui/sortableA11y";
+import { Input } from "./ui/Input";
+import { useReturnFocus } from "./ui/useReturnFocus";
 
 // A playlist's items, grouped for readability: movies stay standalone, while a run of episodes from the
 // same show collapses into a season/show group so a whole series doesn't sprawl into an endless flat
@@ -374,6 +376,7 @@ export default function PlexPlaylistView({
   const qc = useQueryClient();
   const confirm = useConfirm();
   const [renaming, setRenaming] = useState(false);
+  const renameFocus = useReturnFocus(renaming);
   const [name, setName] = useState("");
   const [layout, setLayout] = useState<Layout>(() =>
     getAccountRaw(LS.plexPlaylistLayout) === "tree" ? "tree" : "accordion",
@@ -525,13 +528,25 @@ export default function PlexPlaylistView({
         <div className="mb-4 flex flex-wrap items-center gap-3">
           <div className="min-w-0 flex-1">
             {renaming ? (
-              <input
+              <Input
+                className="w-full text-lg font-bold"
+                size="heading"
                 autoFocus
                 value={name}
                 onChange={(e) => setName(e.target.value)}
-                onKeyDown={(e) => e.key === "Enter" && rename()}
+                onKeyDown={(e) => {
+                  if (e.key === "Enter") {
+                    renameFocus.arm();
+                    rename();
+                  }
+                  // Unmounting the field fires no blur, so Escape really does cancel.
+                  if (e.key === "Escape") {
+                    renameFocus.arm();
+                    setRenaming(false);
+                  }
+                }}
                 onBlur={rename}
-                className="glass-card w-full rounded-lg px-3 py-1.5 text-lg font-bold focus:outline-hidden focus:ring-2 focus:ring-accent/40"
+                aria-label={t("plex.playlist.rename")}
               />
             ) : (
               <h1 className="truncate text-2xl font-bold">{q.data?.title ?? " "}</h1>
@@ -551,6 +566,7 @@ export default function PlexPlaylistView({
             label={t("plex.playlist.layoutLabel")}
           />
           <IconButton
+            ref={renameFocus.target}
             variant="glass"
             size="md"
             onClick={() => {