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/lib/api.ts

@@ -45,10 +45,12 @@ export interface FeedFilters {
   tagMode: "or" | "and";
   q: string;
   sort: string;
+  includeNormal: boolean;
   includeShorts: boolean;
   includeLive: boolean;
   show: string;
   channelId?: string;
+  channelName?: string;
   maxAgeDays?: number;
   minDuration?: number;
   maxDuration?: number;
@@ -78,6 +80,7 @@ function feedQuery(f: FeedFilters, offset: number, limit: number): string {
   p.set("tag_mode", f.tagMode);
   if (f.q) p.set("q", f.q);
   p.set("sort", f.sort);
+  p.set("show_normal", String(f.includeNormal));
   p.set("include_shorts", String(f.includeShorts));
   p.set("include_live", String(f.includeLive));
   p.set("show", f.show);