fix(nav): a linked player, file and search survive what the app does by itself (review round 2)

- Playlists: a link over a playlist the account does not hold plays alone; the rail's own
  fallback no longer counts as a pick that gives the player up.
- The linked opener opens or clears nothing once the address names another player, and stops
  looking (and fetching its row) once it settled.
- Files: a list the server's cap cut — the sorted or searched one too — keeps the link, with a
  notice of its own (EN/HU).
- History: an in-place view rewrite (search refine, count, channel to channel, sub-view)
  drops a reloaded entry's overlay marks (replaceView); a landing on a channel opened from a
  search keeps the search; the Feed press on a search opens the plain feed.
- Files/Playlists: an emptied search is written at once.
- Client log: plf/cf (column text filters) are typed keys; the shell has none of its own.
- Contract: writers outside lib/ take a literal or a lib/ function's result; every URL key is
  sorted typed or not; the writer regexes are held by a fixture; sub-views named; the bookmark
  net reads page tags.
- Feed defaults in one constant; one live-search queue helper; Scheduler writes through the
  Activity codec; notRun copy (EN/HU) names Forward and a plain "Search YouTube" button.

frontend/src/modules/feed/Feed.tsx

@@ -269,7 +269,7 @@ export default function Feed({
   const { setYtCount, askYtSearch } = useNavigationActions();
   // A search runs by itself only where nobody's reload or link can spend quota with it: the free
   // page scrape, or a search asked for in this document. An API search reopened by a reload, a link
-  // or Back waits for "Search YouTube again" — unless its results are still cached, which a disabled
+  // or Back waits for "Search YouTube" — unless its results are still cached, which a disabled
   // query shows all the same. Turned off on this instance it runs too: the server refuses it before
   // any quota, and its refusal is what says so (no press offered that could only be refused).
   const ytRuns = ytActive && (me.search_source !== "api" || ytSearchAsked || !searchOn);
@@ -506,7 +506,7 @@ export default function Feed({
   // The live search's cards, in the order picked for them, and the player's queue over them.
   const ytShown = (rows: Video[]): Video[] =>
     sortYtResults(withOverrides(rows, true), ytSort.key as SortKey, ytSort.dir, lang);
-  const ytQueue = (rows: Video[]): Video[] => ytShown(rows).filter((v) => v.status !== "hidden");
+  const ytQueueOf = (shown: Video[]): Video[] => shown.filter((v) => v.status !== "hidden");
   const merged: Video[] = withOverrides(loaded);
   const items: Video[] = merged.filter((v) => matchesView(v.status, filters.show));
   // The in-app player's queue (auto-advance / loop / prev-next). It's the filtered feed, but the
@@ -520,7 +520,7 @@ export default function Feed({
   // list it was linked over: leaving the search first gives it up.
   useOpenLinkedPlayer(
     ytActive ? ytQuery.data !== undefined || ytQuery.isError || !ytRuns : !query.isLoading,
-    (id) => (ytActive ? ytQueue(ytLoaded) : playerQueue).find((v) => v.id === id),
+    (id) => (ytActive ? ytQueueOf(ytShown(ytLoaded)) : playerQueue).find((v) => v.id === id),
     (video, inList) => {
       openVideo(video);
       // Not in what this list has loaded (further down it, or no longer in it): it plays alone.
@@ -541,7 +541,7 @@ export default function Feed({
   // user explicitly searched, so show everything) and no auto-pagination (each page costs quota).
   if (ytActive) {
     const ytItems: Video[] = ytShown(ytLoaded);
-    const ytPlayerQueue: Video[] = ytItems.filter((v) => v.status !== "hidden");
+    const ytPlayerQueue: Video[] = ytQueueOf(ytItems);
     const ytError =
       ytQuery.error instanceof HttpError
         ? ytQuery.error.detail || t("feed.yt.error")
@@ -649,7 +649,7 @@ export default function Feed({
           <div className="py-16 text-center text-muted">{t("feed.yt.searching")}</div>
         ) : ytError && !ytItems.length ? (
           // A first page that failed is said as the error it is, with Retry where trying again can
-          // help (YouTube busy or unreachable): Search YouTube again with the same term reads the
+          // help (YouTube busy or unreachable): Search YouTube with the same term reads the
           // failure from the cache and sends nothing.
           <StateMessage
             tone="error"