feat: footer, auto-pause on no viewers, and Redsys question submissions

- Footer: add site-footer with one-liner + Cloud Host branding linking to cloudhost.es (mobile only, hidden on desktop)
- Auto-pause: game pauses automatically after AUTOPAUSE_DELAY_MS (default 60s) with no viewers connected; auto-resumes when first viewer connects; shows "Esperando espectadores…" in the UI
- Redsys: new /pregunta page lets viewers pay 1€ via Redsys to submit a fill-in question; submitted questions are used as prompts in the next round instead of AI generation; new redsys.ts implements HMAC_SHA256_V1 signing (3DES key derivation + HMAC-SHA256); notification endpoint at /api/redsys/notificacion handles server-to-server confirmation
- db.ts: questions table with createPendingQuestion / markQuestionPaid / getNextPendingQuestion / markQuestionUsed
- .env.sample: added AUTOPAUSE_DELAY_MS, PUBLIC_URL, REDSYS_* vars

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

broadcast.ts

@@ -35,6 +35,7 @@ type GameState = {
   viewerScores: Record<string, number>;
   done: boolean;
   isPaused: boolean;
+  autoPaused?: boolean;
   generation: number;
 };
 type StateMessage = {