feat: Enhance currency handling and validation across scenarios

- Updated form template to prefill currency input with default value and added help text for clarity.
- Modified integration tests to assert more descriptive error messages for invalid currency codes.
- Introduced new tests for currency normalization and validation in various scenarios, including imports and exports.
- Added comprehensive tests for pricing calculations, ensuring defaults are respected and overrides function correctly.
- Implemented unit tests for pricing settings repository, ensuring CRUD operations and default settings are handled properly.
- Enhanced scenario pricing evaluation tests to validate currency handling and metadata defaults.
- Added simulation tests to ensure Monte Carlo runs are accurate and handle various distribution scenarios.

dependencies.py

@@ -22,6 +22,9 @@ from services.session import (
 )
 from services.unit_of_work import UnitOfWork
 from services.importers import ImportIngestionService
+from services.pricing import PricingMetadata
+from services.scenario_evaluation import ScenarioPricingConfig, ScenarioPricingEvaluator
+from services.repositories import pricing_settings_to_metadata
 
 
 def get_unit_of_work() -> Generator[UnitOfWork, None, None]:
@@ -46,6 +49,29 @@ def get_application_settings() -> Settings:
     return get_settings()
 
 
+def get_pricing_metadata(
+    settings: Settings = Depends(get_application_settings),
+    uow: UnitOfWork = Depends(get_unit_of_work),
+) -> PricingMetadata:
+    """Return pricing metadata defaults sourced from persisted pricing settings."""
+
+    stored = uow.get_pricing_metadata()
+    if stored is not None:
+        return stored
+
+    fallback = settings.pricing_metadata()
+    seed_result = uow.ensure_default_pricing_settings(metadata=fallback)
+    return pricing_settings_to_metadata(seed_result.settings)
+
+
+def get_pricing_evaluator(
+    metadata: PricingMetadata = Depends(get_pricing_metadata),
+) -> ScenarioPricingEvaluator:
+    """Provide a configured scenario pricing evaluator."""
+
+    return ScenarioPricingEvaluator(ScenarioPricingConfig(metadata=metadata))
+
+
 def get_jwt_settings() -> JWTSettings:
     """Provide JWT runtime configuration derived from settings."""