Add admin-frontend and user-frontend standalone projects, certification/invoice/discovery features, fix auth header and theme consistency

backend/app/models/__init__.py

@@ -12,6 +12,8 @@ from .device import Device
 from .followup import FollowupStrategy, FollowupLog
 from .system_config import SystemConfig
 from .translation_quota import TranslationQuota
+from .certification import Certification, CertType, CertStatus
+from .invoice import Invoice, InvoiceType, InvoiceStatus
 
 __all__ = [
     "User", "Product",
@@ -28,4 +30,6 @@ __all__ = [
     "FollowupStrategy", "FollowupLog",
     "SystemConfig",
     "TranslationQuota",
+    "Certification", "CertType", "CertStatus",
+    "Invoice", "InvoiceType", "InvoiceStatus",
 ]