Only warn about staleness for games the reader has switched on

The footer's staleness notice is an instruction, and the only remedy it
offers is "go and check that game's source page". That is not something a
reader can act on for a game they turned off and cannot see a single row
of — and with nineteen lanes, naming eleven they do not play buries the one
they do. A new lane arrives switched off (F8), so an untouched install was
being warned about most of the catalogue.

Scoped in two places, not one: the named list, and the count the
summarising branch measures against. Without the second, that branch would
never fire for a reader with most of the calendar off and they would get a
list where a sentence was the readable answer.

The notice now also states whose games it counted, in the words NextUp
already uses for the same set. Narrowing what the footer measured while
still printing "nothing has refreshed" would turn a claim about four games
into one about eighteen, in the one paragraph on the page whose job is
being trusted about age.

The headline age and the credits stay whole: the first is a fact about the
feed and feeds the bug form, the second is attribution owed to every source
we read regardless of what is on screen.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

src/client/App.tsx

@@ -684,7 +684,14 @@ export function App() {
         </p>
       )}
 
-      <Colophon sources={state.feed.sources} now={now} />
+      {/* `hiddenGames` rather than `enabled`: the footer needs to know what the
+          reader turned *off*, and a lane absent from both is one the feed has
+          and this reader has never been offered — still not theirs to chase. */}
+      <Colophon
+        sources={state.feed.sources}
+        now={now}
+        hiddenGames={prefs.hiddenGames}
+      />
 
       {lastIgnored !== null && (
         <Toast