feat: add environment variable validation to server startup

src/server.ts

@@ -77,14 +77,33 @@ export class WebhookServer {
     }
   }
 
+  static validateEnv() {
+    const missing = REQUIRED_ENV.filter(v => !process.env[v]);
+    if (missing.length) {
+      console.error('❌ Missing required environment variables:');
+      missing.forEach(v => console.error(`- ${v}`));
+      console.error('Add these to your CapRover environment configuration');
+      process.exit(1);
+    }
+
+    if (process.env.CHATBOT_PHONE_NUMBER && 
+        !/^\d+$/.test(process.env.CHATBOT_PHONE_NUMBER)) {
+      console.error('❌ CHATBOT_PHONE_NUMBER must contain only digits');
+      process.exit(1);
+    }
+  }
+
   static start() {
+    this.validateEnv();
+    
+    const PORT = process.env.PORT || 3007;
+    console.log('✅ Environment variables validated');
+    
     if (process.env.NODE_ENV !== 'test') {
-      const server = Bun.serve({
+      return Bun.serve({
         port: PORT,
-        fetch: WebhookServer.handleRequest,
+        fetch: WebhookServer.handleRequest
       });
-      console.log(`Server running on port ${PORT}`);
-      return server;
     }
   }
-} // <-- This closing brace was missing
+}