fix(player): YouTube's fullscreen button stays clickable on a short player

The click layer over the embed left the bottom 22 % of the stage free. YouTube's
new embed keeps its fullscreen button 80-128 px above the iframe's bottom, so on
a stage under ~580 px (a small window, a browser zoomed to 150 %) the layer lay
over it and a click paused instead. The cutouts now have px floors (56 top, 140
bottom) and are measured against the iframe's own box.

frontend/src/components/PlayerModal.dom.test.tsx

@@ -444,6 +444,33 @@ describe("PlayerModal — the side arrows", () => {
   });
 });
 
+// YouTube's embed keeps its fullscreen button at a fixed 80–128 px above the iframe's bottom, its gear
+// and volume along the top. A cutout given only as a share of the height lay over that button on a
+// short player (a small window, a browser zoomed to 150 %): the click paused instead.
+describe("PlayerModal — the click layer over the video", () => {
+  const layer = () => {
+    vi.spyOn(api, "videoDetail").mockReturnValue(new Promise(() => {}));
+    const A = vid("A", 0);
+    renderModal(
+      <PlayerModal video={A} queue={[A]} startIndex={0} onClose={() => {}} onState={() => {}} />,
+    );
+    return screen.getByTestId("yt-click-layer");
+  };
+
+  it("leaves YouTube's own controls a px floor at the top and the bottom, whatever the height", () => {
+    const el = layer();
+    expect(el.style.top).toBe("max(12%, 56px)");
+    expect(el.style.bottom).toBe("max(22%, 140px)");
+  });
+
+  it("measures those edges against the iframe's box, not the stage under our docked bar", () => {
+    const el = layer();
+    expect(el.parentElement!.classList.contains("player-stage")).toBe(false);
+    expect(el.parentElement!.closest(".player-stage")).toBeTruthy();
+    expect(el.parentElement!.className).toMatch(/(^|\s)(relative|absolute)(\s|$)/);
+  });
+});
+
 // At 133% zoom (a 685px window) a full-width card ran 20px past the bottom and cut its channel
 // row. The card's width is capped from the window height less what sits under the video, measured.
 describe("PlayerModal — fits the window's height", () => {