style: apply black and isort formatting

Run formatting tools on Phase 1 changes:
- black (code formatter)
- isort (import sorter)
- ruff (linter)

All linting checks pass.

backend/innercontext/models/__init__.py

@@ -23,6 +23,7 @@ from .enums import (
     UsageFrequency,
 )
 from .health import LabResult, MedicationEntry, MedicationUsage
+from .pricing import PricingRecalcJob
 from .product import (
     ActiveIngredient,
     Product,
@@ -33,7 +34,6 @@ from .product import (
     ProductPublic,
     ProductWithInventory,
 )
-from .pricing import PricingRecalcJob
 from .profile import UserProfile
 from .routine import GroomingSchedule, Routine, RoutineStep
 from .skincare import (