Fix dashboard stats aggregation

backend/app/models/__init__.py

@@ -4,6 +4,7 @@ from app.models.email import Email, EmailFolder
 from app.models.social import Post, Comment, Like, Follow
 from app.models.video import Video, VideoView, VideoLike
 from app.models.file import File, Folder
+from app.models.device import Device, DeviceMetric, DeviceLog
 from app.models.blockchain import Block, Transaction, Wallet
 from app.models.ai_chat import Conversation, Message
 
@@ -20,6 +21,9 @@ __all__ = [
     "VideoLike",
     "File",
     "Folder",
+    "Device",
+    "DeviceMetric",
+    "DeviceLog",
     "Block",
     "Transaction",
     "Wallet",