revert: the Modal Escape guard for a fullscreen own-content video

Chrome does not hand the page the Escape it spends on leaving fullscreen (checked with a real
keypress: the first Esc leaves fullscreen, the second closes the player). The guard defended a case
that does not happen, under a comment saying it does. This reverts 121ebeeb.

frontend/src/components/ui/Modal.tsx

@@ -13,7 +13,7 @@ import { useTranslation } from "react-i18next";
 import { X } from "lucide-react";
 import { useBackToClose } from "../../lib/history";
 import { anyBlockingLayerAbove, pushLayer, removeLayer, takeEscape } from "../../lib/layerStack";
-import { fullscreenElement, useFullscreenPortalHost } from "../../lib/fullscreen";
+import { useFullscreenPortalHost } from "../../lib/fullscreen";
 import { firstFieldIn, focusablesIn, trapTab, useDialogChrome } from "./dialogFocus";
 import { IconButton } from "./IconButton";
 import Toaster from "./Toaster";
@@ -151,11 +151,7 @@ export default function Modal({
     const onKey = (e: KeyboardEvent) => {
       if (takeEscape(e, id)) {
         e.stopPropagation();
-        // The browser spends an Escape on leaving fullscreen and still hands it to the page, the
-        // fullscreen element still set. When that element is the dialog's own content (the library
-        // player's <video>), the Escape was the browser's: closing too lost the viewer the player.
-        const fs = fullscreenElement();
-        if (!(fs && rootRef.current?.contains(fs))) close();
+        close();
         return;
       }
       // Focus trap: keep Tab / Shift+Tab cycling inside the dialog instead of reaching the inert