Add FastAPI backend with agent system

backend/app/routers/__init__.py

@@ -0,0 +1,10 @@
+from app.routers.auth import router as auth_router
+from app.routers.conversation import router as conversation_router
+from app.routers.document import router as document_router
+from app.routers.task import router as task_router
+from app.routers.forum import router as forum_router
+from app.routers.graph import router as graph_router
+from app.routers.agent import router as agent_router
+from app.routers.todo import router as todo_router
+from app.routers.settings import router as settings_router
+from app.routers.folder import router as folder_router