fix(nav): the address follows the view through overlays, reloads and Back (review round 1)

- A URL mirror names the view again on every entry Back or Forward lands on, so a change made
  under a dialog, a drawer or a sub-view is not undone by the next reload.
- A view pushed from the entry a reload under a dialog started from no longer inherits its overlay
  mark; a reload under two overlays closes onto the page in one step.
- The linked player reopens over a live search, gives itself up when its list moves first, and
  plays alone over an emptied playlist; a capped Files list keeps the link it cannot resolve.
- The Feed press over a channel ends the search; leaving a search ends its asked mark; Files and
  Playlists searches end with their page; the feed always names its view and debounces its search.
- Search-box keys are declared per module and kept out of the client log below TRACE.
- Writers outside lib/ go through codecs; the URL contract scans computed keys, overlay writers and
  two-line reads, and holds every page to a bookmark round trip (Config, Activity, Playlists and the
  Files sort and viewer added).

frontend/src/modules/playlists/Playlists.tsx

@@ -583,14 +583,21 @@ function PlaylistDetail() {
   });
   // A reload or a bookmark of the player reopens it once this playlist is in, its view as the queue
   // again (the playlist and its view are in the address under it). A video the view does not show
-  // (filtered out, gone from the list) plays alone, and nothing removes it from a list.
+  // (filtered out, gone from the list, the list emptied or out of reach) plays alone, and nothing
+  // removes it from a list. In: the order seeded from it (an empty one has none to wait for), or its
+  // read refused. Scoped to the playlist it was linked over: another one picked first gives it up.
+  const linkedListIn =
+    (detail != null && (detail.items.length === 0 || items.length > 0)) ||
+    (selectedId != null && detailQuery.isError) ||
+    (selectedId == null && listQuery.data?.length === 0);
   useOpenLinkedPlayer(
-    detail != null && items.length > 0,
+    linkedListIn,
     (id) => shown.find((v) => v.id === id),
     (video, inList) => {
       if (inList) openPlayer(video.id);
       else setPlaying({ video, queue: [video], index: 0, listId: selectedId, editable: false });
     },
+    selectedId,
   );
 
   async function moveItemTo(video: Video, target: Playlist) {