feat(feed): pick the feed's view from its own toolbar

The view mode moves out of Settings into a switcher next to sort, on the
feed and channel pages alike. It leaves the Settings prefs draft for its
own eager save: a toolbar click must not mark that page dirty and trip
its leave-page guard.

lib/feedView.ts owns the vocabulary and maps the old grid/list prefs
forward on read, so nobody's saved choice is lost.

frontend/src/components/VideoCard.tsx

@@ -14,6 +14,7 @@ import AddToPlaylist from "./AddToPlaylist";
 import DownloadButton from "./DownloadButton";
 import clsx from "clsx";
 import type { Video } from "../lib/api";
+import type { FeedView } from "../lib/feedView";
 import { formatDate, formatDuration, formatViews, relativeTime } from "../lib/format";
 
 function Actions({
@@ -237,7 +238,7 @@ function VideoCard({
   onOpen,
 }: {
   video: Video;
-  view: "grid" | "list";
+  view: FeedView;
   onState: (id: string, status: string) => void;
   onResetState?: (id: string) => void;
   onToggleSave: (id: string, saved: boolean) => void;
@@ -303,7 +304,7 @@ function VideoCard({
     </>
   );
 
-  if (view === "list") {
+  if (view === "rows") {
     return (
       <div
         className={clsx(