feat: Add Processing Opex functionality

- Introduced OpexValidationError for handling validation errors in processing opex calculations.
- Implemented ProjectProcessingOpexRepository and ScenarioProcessingOpexRepository for managing project and scenario-level processing opex snapshots.
- Enhanced UnitOfWork to include repositories for processing opex.
- Updated sidebar navigation and scenario detail templates to include links to the new Processing Opex Planner.
- Created a new template for the Processing Opex Planner with form handling for input components and parameters.
- Developed integration tests for processing opex calculations, covering HTML and JSON flows, including validation for currency mismatches and unsupported frequencies.
- Added unit tests for the calculation logic, ensuring correct handling of various scenarios and edge cases.

models/processing_opex_snapshot.py

@@ -0,0 +1,109 @@
+from __future__ import annotations
+
+from datetime import datetime
+from typing import TYPE_CHECKING
+
+from sqlalchemy import JSON, Boolean, DateTime, ForeignKey, Integer, Numeric, String
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy.sql import func
+
+from config.database import Base
+
+if TYPE_CHECKING:  # pragma: no cover
+    from .project import Project
+    from .scenario import Scenario
+    from .user import User
+
+
+class ProjectProcessingOpexSnapshot(Base):
+    """Snapshot of recurring processing opex metrics at the project level."""
+
+    __tablename__ = "project_processing_opex_snapshots"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    project_id: Mapped[int] = mapped_column(
+        ForeignKey("projects.id", ondelete="CASCADE"), nullable=False, index=True
+    )
+    created_by_id: Mapped[int | None] = mapped_column(
+        ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True
+    )
+    calculation_source: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    calculated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    currency_code: Mapped[str | None] = mapped_column(String(3), nullable=True)
+    overall_annual: Mapped[float | None] = mapped_column(Numeric(18, 2), nullable=True)
+    escalated_total: Mapped[float | None] = mapped_column(Numeric(18, 2), nullable=True)
+    annual_average: Mapped[float | None] = mapped_column(Numeric(18, 2), nullable=True)
+    evaluation_horizon_years: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    escalation_pct: Mapped[float | None] = mapped_column(Numeric(12, 6), nullable=True)
+    apply_escalation: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    component_count: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    payload: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+    project: Mapped[Project] = relationship(
+        "Project", back_populates="processing_opex_snapshots"
+    )
+    created_by: Mapped[User | None] = relationship("User")
+
+    def __repr__(self) -> str:  # pragma: no cover
+        return (
+            "ProjectProcessingOpexSnapshot(id={id!r}, project_id={project_id!r}, overall_annual={overall_annual!r})".format(
+                id=self.id,
+                project_id=self.project_id,
+                overall_annual=self.overall_annual,
+            )
+        )
+
+
+class ScenarioProcessingOpexSnapshot(Base):
+    """Snapshot of processing opex metrics for an individual scenario."""
+
+    __tablename__ = "scenario_processing_opex_snapshots"
+
+    id: Mapped[int] = mapped_column(Integer, primary_key=True)
+    scenario_id: Mapped[int] = mapped_column(
+        ForeignKey("scenarios.id", ondelete="CASCADE"), nullable=False, index=True
+    )
+    created_by_id: Mapped[int | None] = mapped_column(
+        ForeignKey("users.id", ondelete="SET NULL"), nullable=True, index=True
+    )
+    calculation_source: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    calculated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    currency_code: Mapped[str | None] = mapped_column(String(3), nullable=True)
+    overall_annual: Mapped[float | None] = mapped_column(Numeric(18, 2), nullable=True)
+    escalated_total: Mapped[float | None] = mapped_column(Numeric(18, 2), nullable=True)
+    annual_average: Mapped[float | None] = mapped_column(Numeric(18, 2), nullable=True)
+    evaluation_horizon_years: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    escalation_pct: Mapped[float | None] = mapped_column(Numeric(12, 6), nullable=True)
+    apply_escalation: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    component_count: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    payload: Mapped[dict | None] = mapped_column(JSON, nullable=True)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+    scenario: Mapped[Scenario] = relationship(
+        "Scenario", back_populates="processing_opex_snapshots"
+    )
+    created_by: Mapped[User | None] = relationship("User")
+
+    def __repr__(self) -> str:  # pragma: no cover
+        return (
+            "ScenarioProcessingOpexSnapshot(id={id!r}, scenario_id={scenario_id!r}, overall_annual={overall_annual!r})".format(
+                id=self.id,
+                scenario_id=self.scenario_id,
+                overall_annual=self.overall_annual,
+            )
+        )