refactor(api): introduce UserContext schema for API dependency injection

Replace direct User database model imports in API endpoints with UserContext
schema, following the architecture principle that API routes should not import
database models directly.

Changes:
- Create UserContext schema in models/schema/auth.py with from_user() factory
- Update app/api/deps.py to return UserContext from all auth dependencies
- Add _get_user_model() helper for functions needing User model access
- Update 58 API endpoint files to use UserContext instead of User
- Add noqa comments for 4 legitimate edge cases (enums, internal helpers)

Architecture validation: 0 errors (down from 61), 11 warnings remain

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/admin/companies.py

@@ -13,7 +13,7 @@ from app.api.deps import get_current_admin_api
 from app.core.database import get_db
 from app.exceptions import CompanyHasVendorsException, ConfirmationRequiredException
 from app.services.company_service import company_service
-from models.database.user import User
+from models.schema.auth import UserContext
 from models.schema.company import (
     CompanyCreate,
     CompanyCreateResponse,
@@ -33,7 +33,7 @@ logger = logging.getLogger(__name__)
 def create_company_with_owner(
     company_data: CompanyCreate,
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Create a new company with owner user account (Admin only).
@@ -87,7 +87,7 @@ def get_all_companies(
     is_active: bool | None = Query(None),
     is_verified: bool | None = Query(None),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """Get all companies with filtering (Admin only)."""
     companies, total = company_service.get_companies(
@@ -128,7 +128,7 @@ def get_all_companies(
 def get_company_details(
     company_id: int = Path(..., description="Company ID"),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Get detailed company information including vendor counts (Admin only).
@@ -179,7 +179,7 @@ def update_company(
     company_id: int = Path(..., description="Company ID"),
     company_update: CompanyUpdate = Body(...),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Update company information (Admin only).
@@ -218,7 +218,7 @@ def toggle_company_verification(
     company_id: int = Path(..., description="Company ID"),
     verification_data: dict = Body(..., example={"is_verified": True}),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Toggle company verification status (Admin only).
@@ -251,7 +251,7 @@ def toggle_company_status(
     company_id: int = Path(..., description="Company ID"),
     status_data: dict = Body(..., example={"is_active": True}),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Toggle company active status (Admin only).
@@ -287,7 +287,7 @@ def transfer_company_ownership(
     company_id: int = Path(..., description="Company ID"),
     transfer_data: CompanyTransferOwnership = Body(...),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Transfer company ownership to another user (Admin only).
@@ -333,7 +333,7 @@ def delete_company(
     company_id: int = Path(..., description="Company ID"),
     confirm: bool = Query(False, description="Must be true to confirm deletion"),
     db: Session = Depends(get_db),
-    current_admin: User = Depends(get_current_admin_api),
+    current_admin: UserContext = Depends(get_current_admin_api),
 ):
     """
     Delete company and all associated vendors (Admin only).