fix(settings): clear an Xtream detail from a hidden category synchronously on relock

The synchronous relock step now clears a selected Xtream item whose
category the visible category list cannot place (a manually hidden
category opened through search), instead of leaving it usable until the
awaited reloads and lookup finish.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/architecture/parental-lock.md

@@ -188,7 +188,9 @@ on either side.
   database answers — ahead of the serialized apply queue, so an earlier
   apply still waiting on a slow or hung read cannot delay it: the selected detail is stepped off synchronously when
   the lock store already names its category (the pre-reload category list
-  maps Electron's row id to the provider id), then `withholdCatalog()`
+  maps Electron's row id to the provider id) or when that list cannot place
+  it at all (a manually hidden category opened through search), then
+  `withholdCatalog()`
   empties every catalog list and `clearSearchResults()` the stored search
   (retiring a search still in flight, which was issued under the previous
   lock state) before the filtered reads refill them; both reloads take a publish guard