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/DebugRecorder.tsx

@@ -26,9 +26,9 @@ import { Button } from "./ui/Button";
 import Modal from "./ui/Modal";
 import { LoadingState, StateMessage } from "./ui/QueryState";
 import SegmentedToggle from "./ui/SegmentedToggle";
-import { inputCls } from "./ui/form";
 import IssueComposer from "./IssueComposer";
 import { useDebugRecording } from "./useDebugRecording";
+import { Input } from "./ui/Input";
 
 // The debug recorder (E16): Start → reproduce → Stop.
 //
@@ -308,14 +308,14 @@ function StepPrompt({ id, onDone }: { id: string; onDone: (label: string | null)
       <label htmlFor="debug-step-label" className="text-sm text-muted">
         {t("recorder.pill.stepPrompt", { n })}
       </label>
-      <input
+      <Input
+        className="w-full"
         id="debug-step-label"
         autoFocus
         value={label}
         onChange={(e) => setStepPrompt(e.target.value)}
         onKeyDown={onKeyDown}
         maxLength={200}
-        className={`${inputCls} w-full`}
       />
       <div className="flex items-center justify-between gap-2 text-xs text-muted">
         <span>{t("recorder.pill.stepHint")}</span>