fix(ci): format setup.py, register CredentialProfile model

- Run ruff format on setup.py to fix pre-existing style violations
- Add CredentialProfile import to models/__init__.py so SQLAlchemy
  can resolve the Device.credential_profile relationship in tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

backend/app/models/__init__.py

@@ -22,6 +22,7 @@ from app.models.config_backup import RouterConfigSnapshot, RouterConfigDiff, Rou
 from app.models.device_interface import DeviceInterface
 from app.models.wireless_link import WirelessLink, LinkState
 from app.models.site_alert import SiteAlertRule, SiteAlertEvent
+from app.models.credential_profile import CredentialProfile
 
 __all__ = [
     "Tenant",
@@ -55,4 +56,5 @@ __all__ = [
     "LinkState",
     "SiteAlertRule",
     "SiteAlertEvent",
+    "CredentialProfile",
 ]