feat(feed): add the small-card, compact-row and tile views

Tiles answer the row view's wasted space: the actions move under the meta
into vertical slack the thumbnail already reserves, which frees ~168px of
width, so the block survives in a narrow column and the list can go
multi-column. Rows stay single-column on purpose — reading down one edge
is why that view exists.

The column count now comes from a per-view minimum width, so every
multi-column view reflows on the mechanism the card grid already used.

frontend/src/components/Feed.tsx

@@ -5,8 +5,11 @@ import {
   ArrowDown,
   ArrowUp,
   ArrowLeft,
+  Columns2,
+  Grid3x3,
   Info,
   LayoutGrid,
+  List,
   RefreshCw,
   Rows3,
   Trash2,
@@ -48,7 +51,10 @@ const rollSeed = () => Math.floor(Math.random() * 1_000_000_000);
 // Icon per view mode; the labels are i18n'd at render (see feed.view.*).
 const VIEW_ICON: Record<FeedView, LucideIcon> = {
   cards: LayoutGrid,
+  cardsSmall: Grid3x3,
   rows: Rows3,
+  rowsCompact: List,
+  tiles: Columns2,
 };
 
 // Ordering = a key + direction (like the Playlists page), mapped to the backend sort strings