fix(ui): keep a context menu open while its own list scrolls

docs/features/playlists.md

@@ -23,7 +23,7 @@ The sidebar's two pinned rows — Liked tracks and Recently played — open the
 
 A **server** playlist gets one item, Open. Every other action takes a local rowid it does not have, and its playback runs through the view's own remote path rather than `player_play_tracks` — so the alternative was a menu with every item greyed out, which is worse than the inert right-click this replaced.
 
-The grid is virtualized, so the menu state lives in [`PlaylistGrid`](../../src/components/views/library/PlaylistGrid.tsx) rather than in a card — a card can unmount under an open menu. `ContextMenu` portals to `body` and closes on scroll, so that unmount is harmless.
+The grid is virtualized, so the menu state lives in [`PlaylistGrid`](../../src/components/views/library/PlaylistGrid.tsx) rather than in a card — a card can unmount under an open menu. `ContextMenu` portals to `body` and closes when the page scrolls, so that unmount is harmless. A scroll inside the menu itself — the playlist list of "Add to a playlist" — leaves it open.
 
 ## Reordering
 

src/components/common/ContextMenu.tsx

@@ -178,18 +178,27 @@ export function ContextMenu({
       if (target?.closest("[data-context-menu]")) return;
       onClose();
     };
+    // Close when the page scrolls — keeps the menu glued to its anchor
+    // without chasing the page. Not when the scroll is inside the menu
+    // itself: the listener captures every scroll, and the playlist
+    // submenu's own list closed the menu the moment it moved.
+    const onScroll = (e: Event) => {
+      const target = e.target;
+      if (target instanceof Element && target.closest("[data-context-menu]")) {
+        return;
+      }
+      onClose();
+    };
     // `mousedown` instead of `click` so dragging doesn't accidentally
     // dismiss before the user releases.
     window.addEventListener("keydown", onKey);
     window.addEventListener("mousedown", onMouseDown);
-    // Close on scroll — keeps the menu glued to its anchor without
-    // chasing the page.
-    window.addEventListener("scroll", onClose, true);
+    window.addEventListener("scroll", onScroll, true);
     window.addEventListener("resize", onClose);
     return () => {
       window.removeEventListener("keydown", onKey);
       window.removeEventListener("mousedown", onMouseDown);
-      window.removeEventListener("scroll", onClose, true);
+      window.removeEventListener("scroll", onScroll, true);
       window.removeEventListener("resize", onClose);
     };
   }, [onClose, menuItems]);

src/components/common/TrackContextMenu.tsx

@@ -139,7 +139,9 @@ export function TrackContextMenu({
         icon={<Plus size={14} />}
         label={t("trackActions.addToPlaylist")}
       >
-        <div className="max-h-64 overflow-y-auto">
+        {/* `overscroll-contain`: reaching the end of the list must not
+            scroll the page behind it, which closes the menu. */}
+        <div className="max-h-64 overflow-y-auto overscroll-contain">
           {playlists.length === 0 ? (
             <div className="px-3 py-2 text-xs text-zinc-400">
               {t("trackActions.noPlaylists")}