feat(player): the side panel's list controls and watch toggle are glyphs on one line

The queue row (previous, count, next, auto-advance, loop) wrapped onto three lines in the
narrow side panel; glyph-only, it fits one. Mark watched joins the action icons as a toggle
(check / double check). Every control keeps its full name and shortcut as its tooltip and
accessible name; the docked bar keeps its labels. The related switch moves up to the toolbar
rung (12px), and its second side reads just "Trending".

frontend/src/features/player/RelatedVideos.dom.test.tsx

@@ -118,6 +118,14 @@ describe("RelatedVideos", () => {
     expect(saved).toHaveBeenCalledWith({ relatedRegion: "hu" });
   });
 
+  it("sets the region switch at the toolbar rung, not the 10px caption one", async () => {
+    vi.spyOn(api, "related").mockResolvedValue(page([row("A")]));
+    setup();
+    await title("Video A");
+    const track = screen.getByRole("group", { name: "player.related.region" });
+    expect(track.className).toMatch(/\btext-xs\b/);
+  });
+
   // A plain pick resumes (null: the player knows the freshest position); the row's own position
   // travels on the video it hands over.
   it("plays a row from where the user left it", async () => {