Much fresher live data: 8s in-play polling, live-TTL summary fetches

The live staleness bug: liveTick refetched ESPN summaries every 20s but
the cache TTL was 5 minutes, so in-play stats/timeline barely moved.
Summaries now take a live flag (15s TTL in play), the scoreboard TTL
drops 20s->5s, and polling gets three tiers (8s in-play / 20s near
kickoff / 10m idle) via a pure, tested cadence module. The
football-data fallback is throttled to one attempt per 15s so the 8s
cadence can never breach its 10 req/min cap. Enrichment runs every 5m
(was 20m); client refetch intervals tighten to 10s (live match page)
and 30s (scoreboard).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/src/tournament.ts

@@ -87,6 +87,11 @@ export class TournamentState {
     );
   }
 
+  /** True only while a match is actually in play. */
+  hasLive(): boolean {
+    return this.fixtures.some((f) => f.status === 'live');
+  }
+
   /** Directly set a fixture's score/status (used by the dev injection endpoint). */
   applyScore(
     num: number,