v3: the lake processed + /data page + glossary terms

- scripts/processStatsbomb.ts: one pass over the 17GB StatsBomb lake (4,235
  matches) -> lakestats.json (12.82GB events / 14.9M events / 6,919 players),
  scorestate.json (goal-rate multipliers by game state — shipped as an insight,
  NOT wired into in-play: the raw effect is selection-biased toward stronger
  teams and would distort a calibrated model), fingerprints.json (40/48 nations'
  shots/xG/set-piece share from real event data). Artifacts committed; raw lake
  stays local (gitignored).
- /data page + /api/data/stats: the gigabytes made visible — lake counters,
  historical archive, live-collection counts (odds lines, frozen forecasts,
  enrichment), per-source health with freshness. Footer links.
- Term component: plain-language glossary tooltips (RPS, Brier, ECE, Elo, xG,
  de-vig, ensemble) attached where metrics appear.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/src/db/db.ts

@@ -177,6 +177,20 @@ export function healthRecord(source: string, ok: boolean, note?: string, openMs?
     });
 }
 
+/** Row counts for the /data page — everything the live layer has collected. */
+export function dbCounts(): Record<string, number> {
+  const c = (sql: string) => (db().prepare(sql).get() as { n: number }).n;
+  return {
+    oddsLines: c('SELECT COUNT(*) n FROM odds_history'),
+    oddsFixtures: c('SELECT COUNT(DISTINCT fixture_num) n FROM odds_history'),
+    frozenForecasts: c('SELECT COUNT(*) n FROM prediction_snapshots'),
+    enrichedMatches: c('SELECT COUNT(*) n FROM match_ext'),
+    mappedFixtures: c('SELECT COUNT(*) n FROM source_map'),
+    cachedResponses: c('SELECT COUNT(*) n FROM kv_cache'),
+    ingestEvents: c('SELECT COUNT(*) n FROM ingest_log'),
+  };
+}
+
 export function logIngest(source: string, job: string, ok: boolean, ms: number, note?: string): void {
   db().prepare('INSERT INTO ingest_log (source, job, ok, ms, note, at) VALUES (?, ?, ?, ?, ?, ?)')
     .run(source, job, ok ? 1 : 0, Math.round(ms), note ?? null, Date.now());