refactor(backend): refactor project, add database migrations support

backend/app/core/queue.py

@@ -0,0 +1,36 @@
+import json
+import os
+from typing import Any, Dict
+import asyncio
+
+RABBITMQ_URL = os.getenv("RABBITMQ_URL") or (
+    f"amqp://{os.getenv('RABBITMQ_USERNAME', 'user')}:"
+    f"{os.getenv('RABBITMQ_PASSWORD', 'bitnami123')}@"
+    f"{os.getenv('RABBITMQ_HOST', 'localhost')}:"
+    f"{os.getenv('RABBITMQ_PORT', '5672')}"
+)
+QUEUE_NAME = os.getenv("MAIL_QUEUE", "mail_queue")
+
+async def _publish_async(message: Dict[str, Any]) -> None:
+    import aio_pika
+    connection = await aio_pika.connect_robust(RABBITMQ_URL)
+    try:
+        channel = await connection.channel()
+        await channel.declare_queue(QUEUE_NAME, durable=True)
+        body = json.dumps(message).encode("utf-8")
+        await channel.default_exchange.publish(
+            aio_pika.Message(body=body, delivery_mode=aio_pika.DeliveryMode.PERSISTENT),
+            routing_key=QUEUE_NAME,
+        )
+    finally:
+        await connection.close()
+
+def enqueue_email(to: str, subject: str, body: str) -> None:
+    message = {"type": "email", "to": to, "subject": subject, "body": body}
+    try:
+        loop = asyncio.get_running_loop()
+        loop.create_task(_publish_async(message))
+    except RuntimeError:
+        asyncio.run(_publish_async(message))
+# ...existing code...
+