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.

services/scenario_evaluation.py

@@ -0,0 +1,54 @@
+from __future__ import annotations
+
+"""Scenario evaluation services including pricing integration."""
+
+from dataclasses import dataclass
+from typing import Iterable, Mapping
+
+from models.scenario import Scenario
+from services.pricing import (
+    PricingInput,
+    PricingMetadata,
+    PricingResult,
+    calculate_pricing,
+)
+
+
+@dataclass(slots=True)
+class ScenarioPricingConfig:
+    """Configuration for pricing evaluation within a scenario."""
+
+    metadata: PricingMetadata | None = None
+
+
+@dataclass(slots=True)
+class ScenarioPricingSnapshot:
+    """Captured pricing results for a scenario."""
+
+    scenario_id: int
+    results: list[PricingResult]
+
+
+class ScenarioPricingEvaluator:
+    """Evaluate scenario profitability inputs using pricing services."""
+
+    def __init__(self, config: ScenarioPricingConfig | None = None) -> None:
+        self._config = config or ScenarioPricingConfig()
+
+    def evaluate(
+        self,
+        scenario: Scenario,
+        *,
+        inputs: Iterable[PricingInput],
+        metadata_override: PricingMetadata | None = None,
+    ) -> ScenarioPricingSnapshot:
+        metadata = metadata_override or self._config.metadata
+        results: list[PricingResult] = []
+        for pricing_input in inputs:
+            result = calculate_pricing(
+                pricing_input,
+                metadata=metadata,
+                currency=scenario.currency,
+            )
+            results.append(result)
+        return ScenarioPricingSnapshot(scenario_id=scenario.id, results=results)