🚚 Refactor and simplify backend file structure (#609)

src/backend/app/api/api_v1/api.py

@@ -0,0 +1,9 @@
+from fastapi import APIRouter
+
+from app.api.api_v1.endpoints import items, login, users, utils
+
+api_router = APIRouter()
+api_router.include_router(login.router, tags=["login"])
+api_router.include_router(users.router, prefix="/users", tags=["users"])
+api_router.include_router(utils.router, prefix="/utils", tags=["utils"])
+api_router.include_router(items.router, prefix="/items", tags=["items"])