feat: Add configurable draw cycles, improve UX, fix builds

Backend:
- Add configurable draw cycle settings (minutes/hourly/daily/weekly/custom)
- Add CYCLE_TYPE, CYCLE_INTERVAL_*, CYCLE_DAILY_TIME, CYCLE_WEEKLY_* env vars
- Add SALES_CLOSE_BEFORE_DRAW_MINUTES and CYCLES_TO_GENERATE_AHEAD
- Fix SQLite parameter issue in scheduler
- Fix TypeScript error in webhooks controller

Frontend:
- Add 'Save This Link' section with copy button on ticket status page
- Improve draw animation to show immediately when draw starts
- Show 'Waiting for next round...' instead of 'Drawing Now!' after draw
- Hide Buy Tickets button when waiting for next round
- Skip draw animation if no tickets were sold
- Keep winner screen open longer (15s) for next cycle to load
- Auto-refresh to next lottery cycle after draw

Telegram Bot:
- Various improvements and fixes

back_end/src/controllers/webhooks.ts

@@ -18,12 +18,12 @@ export async function handleLNbitsPayment(req: Request, res: Response) {
     const webhookSecretQuery = (() => {
       const value = req.query?.secret;
       if (Array.isArray(value)) {
-        return value[0];
+        return typeof value[0] === 'string' ? value[0] : undefined;
       }
-      return value as string | undefined;
+      return typeof value === 'string' ? value : undefined;
     })();
 
-    const providedSecret = webhookSecretHeader || webhookSecretQuery || '';
+    const providedSecret: string = webhookSecretHeader || webhookSecretQuery || '';
 
     if (!lnbitsService.verifyWebhook(providedSecret)) {
       console.error('Webhook verification failed');