fix(player): the stacked layout's minimum width no longer clips the wide one

The 36rem floor guards the stacked layout's width/height feedback loop; the
wide side-panel card has no such loop, and on a short wide window the floor
made the video taller than the card, cutting off YouTube's control bar. The
floor now applies to the stacked layout only; e2e covers a 1400x380 window.

frontend/e2e/player.spec.ts

@@ -29,7 +29,8 @@ test.describe("player modal", () => {
 
 // The video's size, in the windows the owner meets: layout bugs no DOM test can see. Each viewport
 // is a real one — 1920×911 is a 1080p screen at 100% (the side-panel layout), 1097×520 the same
-// screen at 175% or a small laptop at 100% (the stacked layout, on a short window).
+// screen at 175% or a small laptop at 100% (the stacked layout, on a short window), 1400×380 a wide
+// window made short by docked devtools (the side-panel layout, whose card does not scroll).
 test.describe("player modal sizing", () => {
   test.beforeEach(async ({ page }) => {
     await page.route(/youtube\.com/, (route) => route.abort());
@@ -41,6 +42,7 @@ test.describe("player modal sizing", () => {
   for (const [w, h] of [
     [1920, 911],
     [1097, 520],
+    [1400, 380],
   ] as const) {
     test(`the video keeps a real size at ${w}×${h}, and maximised fills the window`, async ({
       page,
@@ -54,6 +56,16 @@ test.describe("player modal sizing", () => {
       const stage = await box(page, ".player-stage");
       expect(stage.width).toBeGreaterThanOrEqual(Math.min(w * 0.5, 560));
       expect(stage.height).toBeGreaterThan(stage.width * 0.5);
+      // …and all of it is in sight: its bottom edge is the YouTube control bar, and the side-panel
+      // card clips what overflows it (it does not scroll), the stacked card scrolls to it.
+      const overflow = await page
+        .locator(".player-stage")
+        .first()
+        .evaluate((el) => {
+          const card = el.parentElement!;
+          return el.getBoundingClientRect().bottom - card.getBoundingClientRect().bottom;
+        });
+      expect(overflow).toBeLessThanOrEqual(0.5);
 
       // Maximise (F): the stage is fixed to the viewport. In the side-panel layout its `self-start`
       // once aligned the fixed box too, and it shrank to its content's height — 0 px, a thin line.