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/Scheduler.tsx

@@ -259,6 +259,7 @@ function MaintenanceSettings({
           value={val}
           onChange={(e) => setVal(e.target.value)}
           onKeyDown={(e) => e.key === "Enter" && save()}
+          aria-label={t("scheduler.maintenance.batchLabel")}
           className="w-28 bg-card border border-border rounded px-2 py-1 text-sm tabular-nums outline-none focus:border-accent"
         />
         <button