style(frontend): Prettier config + one-time repo-wide format pass

Prettier 3 (pinned), printWidth 100, double quotes — chosen to match the existing
hand-formatting and minimise reflow. This commit is ONLY the mechanical format pass
(`prettier --write`) plus the config/ignore/scripts, isolated so it never pollutes a
feature diff. Verified behaviour-neutral: typecheck, eslint (0 errors), and vitest
all green before and after. See .git-blame-ignore-revs — `git blame` skips this sha.

frontend/src/components/ChannelDiscovery.tsx

@@ -91,7 +91,7 @@ export default function ChannelDiscovery({
 
   const q = search.trim().toLowerCase();
   const rows = (query.data ?? []).filter(
-    (c) => !q || `${c.title ?? ""} ${c.handle ?? ""}`.toLowerCase().includes(q)
+    (c) => !q || `${c.title ?? ""} ${c.handle ?? ""}`.toLowerCase().includes(q),
   );
 
   const columns: Column<DiscoveredChannel>[] = [
@@ -107,9 +107,7 @@ export default function ChannelDiscovery({
       render: (c) => (
         <Tooltip
           hint={
-            canWrite
-              ? t("channels.discovery.subscribeHint")
-              : t("channels.discovery.needWriteHint")
+            canWrite ? t("channels.discovery.subscribeHint") : t("channels.discovery.needWriteHint")
           }
         >
           <button
@@ -189,11 +187,11 @@ export default function ChannelDiscovery({
   // copy+sort the whole list every render for a result nothing reads.
   const isCards = layout === "cards";
   const sortedRows = isCards ? sortRows(rows, columns, sort) : rows;
-  const { paged: pagedRows, pagerProps, resetPage } = useCardPager(
-    sortedRows,
-    LS.channelDiscoveryCardSize,
-    isCards,
-  );
+  const {
+    paged: pagedRows,
+    pagerProps,
+    resetPage,
+  } = useCardPager(sortedRows, LS.channelDiscoveryCardSize, isCards);
   // Changing what you're looking at starts over at the first page. NOT keyed on the row count:
   // subscribing drops a row from this tab, and being thrown to page 1 for it would punish the very
   // action you just took — a list that shrank past your page is handled by the hook's clamp.