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.

models/project.py

@@ -4,7 +4,7 @@ from datetime import datetime
 from enum import Enum
 from typing import TYPE_CHECKING, List
 
-from sqlalchemy import DateTime, Enum as SQLEnum, Integer, String, Text
+from sqlalchemy import DateTime, Enum as SQLEnum, ForeignKey, Integer, String, Text
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 from sqlalchemy.sql import func
 
@@ -12,6 +12,7 @@ from config.database import Base
 
 if TYPE_CHECKING:  # pragma: no cover
     from .scenario import Scenario
+    from .pricing_settings import PricingSettings
 
 
 class MiningOperationType(str, Enum):
@@ -38,6 +39,10 @@ class Project(Base):
         SQLEnum(MiningOperationType), nullable=False, default=MiningOperationType.OTHER
     )
     description: Mapped[str | None] = mapped_column(Text, nullable=True)
+    pricing_settings_id: Mapped[int | None] = mapped_column(
+        ForeignKey("pricing_settings.id", ondelete="SET NULL"),
+        nullable=True,
+    )
     created_at: Mapped[datetime] = mapped_column(
         DateTime(timezone=True), nullable=False, server_default=func.now()
     )
@@ -51,6 +56,10 @@ class Project(Base):
         cascade="all, delete-orphan",
         passive_deletes=True,
     )
+    pricing_settings: Mapped["PricingSettings | None"] = relationship(
+        "PricingSettings",
+        back_populates="projects",
+    )
 
     def __repr__(self) -> str:  # pragma: no cover - helpful for debugging
         return f"Project(id={self.id!r}, name={self.name!r})"