Wave 2B: reliable cross-sport headshots via ESPN athlete index

The NBA/WNBA espnId was captured only from espnStatsAdapter (the offline-
Python fallback), unreliable in prod. Add espnAthleteIndex — a pure,
defensive harvester that builds { nameKey -> {espnId, headshotHref} } from
the ESPN schedule->summary/boxscore/leaders/injuries/roster feeds the
pipeline already calls (free, bounded mapLimit, cached, MLB->{}).

snapshotService now fills any player the primary stats-resolve left without
an espnId from this index, and stores a DIRECT headshotHref as headshotUrl
on the enriched grade (the exact URL, never 404s on a constructed path).
Threaded headshotUrl through slateAdapter.buildPlayerStripsFromProps ->
GameCard -> StatStrip -> PlayerAvatar/getHeadshotUrl (direct href wins over
the constructed one). MLB's MLBAM path is untouched. Soccer resolves only
via a direct href; absent -> honest monogram (API_FOOTBALL_KEY remains the
reliable soccer path, unwired).

getGameSummary now also passes through ESPN `rosters` (pre-game lineups
carry id + headshot). Everything graceful: any miss -> absent -> monogram.

Tests: tests/unit/espnHeadshotIndex.test.js (11) — fixture->index, snapshot
merge fallback, direct-href-wins, soccer honest monogram, malformed/cyclic
parse never throws. Full suite 3080 green; web next build exit 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/lib/playerHeadshot.ts

@@ -33,6 +33,8 @@ export interface HeadshotInput {
   playerId?: string | number | null;
   /** ESPN athlete ID — the NBA/WNBA (and dormant NFL/NHL) headshot source. */
   espnId?: string | number | null;
+  /** Wave 2B — a RESOLVED absolute headshot URL (ESPN's exact href); wins over a constructed one. */
+  headshotUrl?: string | null;
   /** Pre-cached photo URL (used by soccer where each league has no central CDN). */
   cachedPhotoUrl?: string | null;
 }