feat(client): state in the footer when event data last refreshed

The footer only spoke up past the two-day threshold, and then only as a
count of stale sources. A page silent about its own age reads as current,
so it now says when the data last refreshed on every load — absolute date
plus relative age, next to where the warning appears. This is the half of
PRD F7 that was never built.

Where the number comes from is the whole point. `freshness()` in
src/shared/feed.ts takes the newest lastSuccessAt and never generatedAt:
the feed is rebuilt on every deploy whether or not anything was refetched,
so a build stamp would report a calendar as minutes old while its events
came from a fixture captured months ago. A game is also only as fresh as
its oldest source, or Endfield's live wiki would vouch for its stalled
Game8 page. That matters concretely here — eight sources cannot be fetched
from CI at all, so this notice is what stands between a reader and a
confidently stale calendar.

The stale warning now names the lagging games and how far behind each is,
because a count is not something a reader can act on while a name tells
them which source page to check. Two exceptions found by rendering it
against the real feed: past four games it summarises the remainder, and
when every game is behind — what a refresh that stopped running looks like
— it collapses to one sentence rather than ten names repeating one age.

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

src/client/App.tsx

@@ -27,7 +27,7 @@ import {
   outstanding,
   resolveFocus,
 } from "./state/lens.ts";
-import { clockFor, DAY, formatRemaining } from "../shared/time.ts";
+import { clockFor, formatRemaining } from "../shared/time.ts";
 import { dailySummary, isDaily, resolveDaily } from "../shared/daily.ts";
 import { GameMetaProvider, type MetaResolver } from "./state/gameMeta.tsx";
 import {
@@ -295,10 +295,6 @@ export function App() {
     );
   }
 
-  const staleSources = state.feed.sources.filter(
-    (s) => s.lastSuccessAt === null || now - Date.parse(s.lastSuccessAt) > 2 * DAY,
-  );
-
   return (
     <GameMetaProvider value={gameMeta}>
     <Shell>
@@ -503,7 +499,7 @@ export function App() {
         </p>
       )}
 
-      <Colophon sources={state.feed.sources} staleCount={staleSources.length} />
+      <Colophon sources={state.feed.sources} now={now} />
 
       {lastIgnored !== null && (
         <Toast