feat: add environment variables validation

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/env.js

@@ -0,0 +1,32 @@
+import logger from './utils/logger.js';
+
+const requiredEnv = {
+  BOT_TOKEN: process.env.BOT_TOKEN,
+  STORAGE_CHANNEL_ID: process.env.STORAGE_CHANNEL_ID,
+  BASE_URL: process.env.BASE_URL,
+  DATABASE_URL: process.env.DATABASE_URL,
+  PORT: process.env.PORT
+};
+
+const missing = Object.entries(requiredEnv)
+  .filter(([_, value]) => value === undefined || value === '')
+  .map(([key]) => key);
+
+if (missing.length > 0) {
+  logger.error('Missing required environment variables:', missing);
+  throw new Error(`Missing environment variables: ${missing.join(', ')}`);
+}
+
+export const config = {
+  botToken: process.env.BOT_TOKEN,
+  storageChatId: parseInt(process.env.STORAGE_CHANNEL_ID, 10),
+  baseUrl: process.env.BASE_URL,
+  databaseUrl: process.env.DATABASE_URL,
+  port: parseInt(process.env.PORT, 10) || 3000,
+  nodeEnv: process.env.NODE_ENV || 'development',
+  logLevel: process.env.LOG_LEVEL || 'info',
+  rateLimitWindowMs: parseInt(process.env.RATE_LIMIT_WINDOW_MS, 10) || 60000,
+  rateLimitMaxRequests: parseInt(process.env.RATE_LIMIT_MAX_REQUESTS, 10) || 30
+};
+
+logger.info('Environment variables loaded', { config: { ...config, botToken: config.botToken?.substring(0, 10) + '...' } });