feat: added .env configuration for global app, database and jwt

Refs: #2

src/main.ts

@@ -1,8 +1,18 @@
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
+import { ConfigService } from '@nestjs/config';
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
-  await app.listen(process.env.PORT ?? 3000);
+
+  const configService = app.get(ConfigService);
+
+  const port = configService.get<number>('app.port', 3000);
+  await app.listen(port);
+  console.log(`✅ P'titsPas API is running on: ${await app.getUrl()}`);
 }
-bootstrap();
+
+bootstrap().catch((err) => {
+  console.error('❌ Error starting the application:', err);
+  process.exit(1);
+});