feat(nav): tabs, list views and name searches are named in the address

Settings, Configuration and Users name their tab (stab/cfgtab/utab); a link's tab wins and a tab pre-selected
while its page is on screen now switches it. A playlist's sort, filters and grouping (plsort/plf/plgroup), the
Files sort (fsort, always written) and the name searches of Channels, Files, Playlists and Plex (cq/fq/plq/pq+pqf)
reopen from the address; the searches are written once the typing pauses.

frontend/src/modules/channels/ChannelsProvider.tsx

@@ -15,6 +15,7 @@ import { useSortState } from "../../lib/useSortState";
 import { usePref } from "../../lib/usePref";
 import { useFilterState } from "../../lib/useFilterState";
 import { useUrlMirror } from "../../lib/useUrlMirror";
+import { useDebounced } from "../../lib/useDebounced";
 import { rememberNavPosition } from "../../lib/history";
 import {
   channelsParamsToState,
@@ -43,7 +44,8 @@ import {
 //
 // Nested INSIDE NavigationProvider so its actions can drive navigation: focusChannel and
 // goToFullHistory both jump to the Channels page (and force the subscriptions tab). filters / view are
-// per-account persisted (localStorage); search / focus / the reset token are ephemeral. An account
+// per-account persisted (localStorage); the search lives only in the address (below); focus and the
+// reset token are ephemeral. An account
 // switch does a full reload, so init-from-storage is all the hydration the persisted ones need.
 //
 // The contexts, their value types and the hooks live in channelsContext.ts.
@@ -93,6 +95,7 @@ function readChannelsUrlSeed(): ChannelsUrlState | null {
     view: clampView(getAccountRaw(LS.channelsView)),
     sort: hydrateSort(getAccountRaw(LS.channelSort), [], null),
     filters: readStoredFilters(),
+    search: "",
   });
 }
 
@@ -101,7 +104,11 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
   const { page } = nav;
   const { setPage } = useNavigationActions();
 
-  const [search, setSearchState] = useState("");
+  // Shareable manager view. Captured once at mount (or null when no manager URL keys are present).
+  const [urlSeed] = useState(readChannelsUrlSeed);
+  const seededRef = useRef(false);
+
+  const [search, setSearchState] = useState(() => urlSeed?.search ?? "");
   // The subscribed table's column-filter map, owned here (lifted out of DataTable) so the top status
   // chips, the Sync column funnel, and the card layout share one state; useFilterState persists it.
   const [filters, setFilters] = useFilterState(LS.channelsFilterMap, migrateSyncChip);
@@ -122,10 +129,6 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
   const [focusNameRaw, setFocusName] = useState<string | null>(null);
   const [focusToken, setFocusToken] = useState(0);
 
-  // Shareable manager view. Captured once at mount (or null when no manager URL keys are present).
-  const [urlSeed] = useState(readChannelsUrlSeed);
-  const seededRef = useRef(false);
-
   // Apply the shared-link seed once, BEFORE paint, through the slice setters — which persist it, so the
   // shared view also survives a later PLAIN reload (no URL). setViewRaw (not setView) restores the tab
   // without pushing a phantom history entry. A normal load has urlSeed === null and this is a no-op.
@@ -247,12 +250,17 @@ export function ChannelsProvider({ children }: { children: ReactNode }) {
     ],
   );
 
-  // Mirror the content state (tab + sort + column filters) into the address bar under the namespaced
-  // keys so a manager view is shareable. Gated on urlPage===channels: off the manager (or under a channel
-  // page) the keys are cleared
-  // (localStorage still holds the state; it re-mirrors on return). The name `search` stays OUT — it's a
-  // deliberately transient rail-search, like the feed's and plex's.
-  useUrlMirror(channelsParamUpdates(urlPage(nav) === "channels" ? { view, sort, filters } : null));
+  // Mirror the content state (tab + sort + column filters + the name search) into the address bar under
+  // the namespaced keys so a manager view is shareable. Gated on urlPage===channels: off the manager (or
+  // under a channel page) the keys are cleared (localStorage still holds the rest; it re-mirrors on
+  // return; the search is this visit's). The search is written once the typing pauses: one address-bar
+  // write per keystroke is history churn a browser throttles.
+  const typed = useDebounced(search, 300);
+  useUrlMirror(
+    channelsParamUpdates(
+      urlPage(nav) === "channels" ? { view, sort, filters, search: typed } : null,
+    ),
+  );
 
   return (
     <ChannelsActionsContext.Provider value={actions}>