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/NavSidebar.tsx

@@ -258,7 +258,6 @@ export default function NavSidebar({
             onClick={() => setPage("feed")}
             className="text-lg font-bold tracking-tight select-none cursor-pointer rounded-md -mx-1 px-1 hover:bg-card hover:opacity-90 transition"
             title={t("header.feed")}
-            aria-label={t("header.feed")}
           >
             Sift<span className="text-accent">lode</span>
           </button>