fix(a11y): accessible names for switches, swatches, selects and inputs

Lighthouse a11y across the authenticated module pages flagged: the clickable
Siftlode logo had aria-label='Feed' (accessible name didn't include its visible
text); the shared Switch, theme swatches, sort selects and several number/range
inputs had no accessible name/label. Give Switch role='switch'+aria-checked and
an optional label (passed at every call site), aria-label the swatches, selects
(feed/playlists sort) and the settings/config/scheduler inputs, and drop the
mismatched logo aria-label so its visible text is the name. All 11 module pages
now score 100 accessibility (settings 86->100, playlists 89->100, others 92-95->100).

frontend/src/components/Playlists.tsx

@@ -140,6 +140,7 @@ function Row({
       <span className="text-xs text-muted w-4 text-center tabular-nums">{index + 1}</span>
       <button
         onClick={onPlay}
+        aria-label={`${t("card.play")} — ${video.title}`}
         className="relative w-[62px] h-[35px] rounded overflow-hidden bg-surface shrink-0 group"
       >
         {video.thumbnail_url && (
@@ -540,6 +541,7 @@ export default function Playlists({ canWrite }: { canWrite: boolean }) {
               onChange={(e) =>
                 setPlSort({ ...plSort, key: e.target.value as PlSort["key"] })
               }
+              aria-label={t("playlists.sortLabel")}
               className="flex-1 min-w-0 bg-card border border-border rounded-md px-1.5 py-1 text-[11px] outline-none focus:border-accent"
             >
               <option value="custom">{t("playlists.railSortCustom")}</option>