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/Scheduler.tsx

@@ -28,6 +28,7 @@ import Tooltip from "./ui/Tooltip";
 import { notifyActionError } from "../lib/actionErrors";
 import { IconButton } from "./ui/IconButton";
 import { Pressable } from "./ui/Pressable";
+import { Input } from "./ui/Input";
 
 const POLL_MS = 4000;
 // While any job is running, poll faster so short scheduled runs aren't missed between ticks.
@@ -181,7 +182,10 @@ function JobRow({
           </Tooltip>
           {editing ? (
             <span className="inline-flex items-center gap-1">
-              <input
+              <Input
+                className="w-16"
+                size="xs"
+                invalid={!valid}
                 type="number"
                 min={1}
                 max={1440}
@@ -194,11 +198,6 @@ function JobRow({
                   if (e.key === "Enter") save();
                   if (e.key === "Escape") close();
                 }}
-                className={`w-16 bg-surface border rounded-sm px-1.5 py-0.5 text-xs focus:outline-hidden focus:ring-2 ${
-                  valid
-                    ? "border-border focus:ring-accent/40"
-                    : "border-danger focus:ring-danger/40"
-                }`}
               />
               <span className="text-muted text-xs">{t("scheduler.minutes")}</span>
               <IconButton onClick={save} disabled={saving || !valid} label={t("common.save")}>
@@ -306,7 +305,10 @@ function MaintenanceSettings({
           </span>
         </Tooltip>
         <span className="flex-1" />
-        <input
+        <Input
+          className="w-28 tabular-nums"
+          size="sm"
+          invalid={!valid}
           type="number"
           min={m.min}
           max={m.max}
@@ -320,9 +322,6 @@ function MaintenanceSettings({
           aria-label={t("scheduler.maintenance.batchLabel")}
           aria-invalid={!valid}
           aria-errormessage={valid ? undefined : rangeId}
-          className={`w-28 bg-surface border rounded-sm px-2 py-1 text-sm tabular-nums focus:outline-hidden focus:ring-2 ${
-            valid ? "border-border focus:ring-accent/40" : "border-danger focus:ring-danger/40"
-          }`}
         />
         <Button variant="glass" size="sm" onClick={save} disabled={!dirty || saving || !valid}>
           {t("common.save")}