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/config/index.ts

@@ -0,0 +1,50 @@
+import dotenv from 'dotenv';
+
+dotenv.config();
+
+function required(name: string): string {
+  const value = process.env[name];
+  if (!value) {
+    throw new Error(`Missing required environment variable: ${name}`);
+  }
+  return value;
+}
+
+function optional(name: string, defaultValue: string): string {
+  return process.env[name] || defaultValue;
+}
+
+function optionalInt(name: string, defaultValue: number): number {
+  const value = process.env[name];
+  if (!value) return defaultValue;
+  const parsed = parseInt(value, 10);
+  return isNaN(parsed) ? defaultValue : parsed;
+}
+
+export const config = {
+  telegram: {
+    botToken: required('TELEGRAM_BOT_TOKEN'),
+  },
+  api: {
+    baseUrl: optional('API_BASE_URL', 'http://localhost:3000'),
+  },
+  frontend: {
+    baseUrl: optional('FRONTEND_BASE_URL', 'http://localhost:3001'),
+  },
+  redis: {
+    url: process.env.REDIS_URL || null,
+  },
+  bot: {
+    maxTicketsPerPurchase: optionalInt('MAX_TICKETS_PER_PURCHASE', 100),
+    paymentPollIntervalMs: optionalInt('PAYMENT_POLL_INTERVAL_MS', 5000),
+    paymentPollTimeoutMs: optionalInt('PAYMENT_POLL_TIMEOUT_MS', 900000), // 15 minutes
+    invoiceExpiryMinutes: optionalInt('INVOICE_EXPIRY_MINUTES', 15),
+  },
+  logging: {
+    level: optional('LOG_LEVEL', 'info'),
+  },
+  nodeEnv: optional('NODE_ENV', 'development'),
+};
+
+export default config;
+