fix(ui): review round 2 — reveal floor, failed next page, count states, row Play

- DataTable: the reveal floor holds only in the view it was made for (Channels
  never clears its follow, so every later sort mounted rows up to it)
- Feed + Plex browse: a failed next page stops the read-ahead and shows a row
  that retries, instead of re-requesting it once a round-trip
- the YouTube Load more click uses nextPageOnClick; a contract pins NEXT_PAGE
  to the read-aheads and the click sites to nextPageOnClick
- ItemCount: a failed count says so; a stale one says updating to a screen reader
- the narrow-picture Play lift applies only where a hover row is there to clear
- PlayerModal: one description ladder for the popover and the panel, both tested
- plexImage contract reads every img src, any attribute order
- Tabs comment names who persists the sub-tab

frontend/src/components/PlayerModal.tsx

@@ -6,6 +6,7 @@ import {
   useLayoutEffect,
   useRef,
   useState,
+  type ReactNode,
 } from "react";
 import { useTranslation } from "react-i18next";
 import { createPortal } from "react-dom";
@@ -606,6 +607,30 @@ export default function PlayerModal({
     qc,
   });
 
+  // The description, said the same way in its two places (the popover under 1280 px, the panel
+  // beside the video above it): loading, failed with a retry, the text, or none. One ladder, so the
+  // two cannot drift (E31 review 2: the failed state was tested in the panel only). `wrap` is each
+  // place's own box for the text.
+  const description = (wrap: (body: ReactNode) => ReactNode) =>
+    detail.isLoading ? (
+      <div className="text-sm text-muted">{t("player.loading")}</div>
+    ) : detail.isError && !detail.data ? (
+      <StateMessage tone="error" compact onRetry={() => void detail.refetch()}>
+        {t("player.descriptionFailed")}
+      </StateMessage>
+    ) : detail.data?.description ? (
+      wrap(
+        renderDescription(detail.data.description, {
+          currentId: currentVideoId,
+          onSeek: seekTo,
+          onLoadVideo: loadVideo,
+          t,
+        }),
+      )
+    ) : (
+      <div className="text-sm text-muted">{t("player.noDescription")}</div>
+    );
+
   // Portaled to <body>, like every other full-screen overlay here. A fixed, full-viewport modal
   // must not render inside the page scroller: once that scroller is a stacking context (its
   // edge-fade mask makes it one) this z-overlay is scoped inside it, and the nav rail (z-rail) and the
@@ -887,28 +912,15 @@ export default function PlayerModal({
                     <SectionLabel level={3} className="mb-2">
                       {t("player.description")}
                     </SectionLabel>
-                    {detail.isLoading ? (
-                      <div className="text-sm text-muted">{t("player.loading")}</div>
-                    ) : detail.isError && !detail.data ? (
-                      <StateMessage tone="error" compact onRetry={() => void detail.refetch()}>
-                        {t("player.descriptionFailed")}
-                      </StateMessage>
-                    ) : detail.data?.description ? (
+                    {description((body) => (
                       <div
                         ref={descFade.ref}
                         style={descFade.style}
                         className="text-sm whitespace-pre-wrap wrap-break-word max-h-64 overflow-y-auto no-scrollbar leading-relaxed"
                       >
-                        {renderDescription(detail.data.description, {
-                          currentId: currentVideoId,
-                          onSeek: seekTo,
-                          onLoadVideo: loadVideo,
-                          t,
-                        })}
+                        {body}
                       </div>
-                    ) : (
-                      <div className="text-sm text-muted">{t("player.noDescription")}</div>
-                    )}
+                    ))}
                   </PopoverSurface>
                   <Button
                     variant="ghost"
@@ -1089,24 +1101,11 @@ export default function PlayerModal({
                     <SectionLabel level={3} className="mb-2">
                       {t("player.description")}
                     </SectionLabel>
-                    {detail.isLoading ? (
-                      <div className="text-sm text-muted">{t("player.loading")}</div>
-                    ) : detail.isError && !detail.data ? (
-                      <StateMessage tone="error" compact onRetry={() => void detail.refetch()}>
-                        {t("player.descriptionFailed")}
-                      </StateMessage>
-                    ) : detail.data?.description ? (
+                    {description((body) => (
                       <div className="text-sm whitespace-pre-wrap wrap-break-word leading-relaxed">
-                        {renderDescription(detail.data.description, {
-                          currentId: currentVideoId,
-                          onSeek: seekTo,
-                          onLoadVideo: loadVideo,
-                          t,
-                        })}
+                        {body}
                       </div>
-                    ) : (
-                      <div className="text-sm text-muted">{t("player.noDescription")}</div>
-                    )}
+                    ))}
                   </section>
                 )}
               </div>