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/DownloadDialog.tsx

@@ -12,8 +12,8 @@ const ProfileEditor = lazy(() => import("./ProfileEditor"));
 import { notify } from "../lib/notifications";
 import { notifyActionError } from "../lib/actionErrors";
 import { navigateTo } from "../lib/nav";
-import { inputCls } from "./ui/form";
 import FilterSelect from "./ui/FilterSelect";
+import { Input } from "./ui/Input";
 
 // Preset picker shown when the user hits Download on a card / in the player, or adds a URL from
 // the Download Center. Enqueues via the API and points the user at the Download Center.
@@ -82,11 +82,11 @@ export default function DownloadDialog({
       </Button>
 
       <label className="block text-sm font-medium mb-1">{t("downloads.dialog.nameLabel")}</label>
-      <input
+      <Input
+        className="w-full mb-5"
         value={name}
         onChange={(e) => setName(e.target.value)}
         placeholder={t("downloads.dialog.namePlaceholder")}
-        className={`${inputCls} mb-5`}
       />
 
       <div className="flex justify-end gap-2">