feat: Add Telegram bot with group support

- Full Telegram bot implementation for Lightning Jackpot
- Commands: /start, /buy, /tickets, /wins, /address, /jackpot, /help
- Lightning invoice generation with QR codes
- Payment polling and confirmation notifications
- User state management (Redis/in-memory fallback)
- Group support with admin settings panel
- Configurable draw announcements and reminders
- Centralized messages for easy i18n
- Docker configuration included

telegram_bot/src/services/qr.ts

@@ -0,0 +1,27 @@
+import QRCode from 'qrcode';
+import { logger } from './logger';
+
+/**
+ * Generate a QR code as a buffer from a Lightning invoice
+ */
+export async function generateQRCode(data: string): Promise<Buffer> {
+  try {
+    const buffer = await QRCode.toBuffer(data.toUpperCase(), {
+      errorCorrectionLevel: 'M',
+      type: 'png',
+      margin: 2,
+      width: 300,
+      color: {
+        dark: '#000000',
+        light: '#FFFFFF',
+      },
+    });
+    return buffer;
+  } catch (error) {
+    logger.error('Failed to generate QR code', { error });
+    throw error;
+  }
+}
+
+export default { generateQRCode };
+