chore: 将后端移动到 api/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/api/asgi.py

@@ -0,0 +1,30 @@
+"""
+ASGI config for api project.
+
+It exposes the ASGI callable as a module-level variable named ``application``.
+
+For more information on this file, see
+https://docs.djangoproject.com/en/5.1/howto/deployment/asgi/
+"""
+
+import os
+
+os.environ.setdefault("DJANGO_SETTINGS_MODULE", "api.settings")
+
+from django.core.asgi import get_asgi_application
+
+django_asgi_app = get_asgi_application()
+
+from channels.routing import ProtocolTypeRouter, URLRouter
+from channels.auth import AuthMiddlewareStack
+from channels.security.websocket import AllowedHostsOriginValidator
+from prompt.url import websocket_urlpatterns
+
+application = ProtocolTypeRouter(
+    {
+        "http": django_asgi_app,
+        "websocket": AllowedHostsOriginValidator(
+            AuthMiddlewareStack(URLRouter(websocket_urlpatterns))
+        ),
+    }
+)