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/Feed.tsx

@@ -579,6 +579,7 @@ export default function Feed({
               seed: key === "shuffle" ? rollSeed() : undefined,
             });
           }}
+          aria-label={t("feed.sortLabel")}
           className="bg-card border border-border rounded-lg px-2 py-1.5 text-sm outline-none focus:border-accent"
         >
           {/* Relevance only ranks meaningfully when there's a search term — offer it then. */}