feat: feedback round 3 — content-type toggles, channel filter, card polish

- Content type is now three independent toggles (Normal / Shorts / Live·Upcoming);
  the feed is the union of enabled types (backend show_normal + include_shorts +
  include_live)
- Per-channel filter: a button on each card scopes the feed to that channel, shown
  as a removable chip in the sidebar
- Hide now refetches the feed once the change is persisted, so a hidden video shows
  up in the Hidden view immediately (no refresh needed); optimistic updates respect
  the current view
- Grid cards are now distinct panels (card background, border, shadow) that lift on
  hover; clickable channel name in list view too

frontend/src/App.tsx

@@ -19,6 +19,7 @@ const DEFAULT_FILTERS: FeedFilters = {
   tagMode: "or",
   q: "",
   sort: "newest",
+  includeNormal: true,
   includeShorts: false,
   includeLive: false,
   show: "unwatched",
@@ -96,7 +97,7 @@ export default function App() {
       <div className="flex flex-1 min-h-0">
         <Sidebar filters={filters} setFilters={setFilters} />
         <main className="flex-1 min-w-0 overflow-y-auto">
-          <Feed filters={filters} view={view} />
+          <Feed filters={filters} setFilters={setFilters} view={view} />
         </main>
       </div>
       <Toaster />