feat: Add profitability calculation schemas and service functions

- Introduced Pydantic schemas for profitability calculations in `schemas/calculations.py`.
- Implemented service functions for profitability calculations in `services/calculations.py`.
- Added new exception class `ProfitabilityValidationError` for handling validation errors.
- Created repositories for managing project and scenario profitability snapshots.
- Developed a utility script for verifying authenticated routes.
- Added a new HTML template for the profitability calculator interface.
- Implemented a script to fix user ID sequence in the database.

services/exceptions.py

@@ -26,3 +26,14 @@ class ScenarioValidationError(Exception):
 
     def __str__(self) -> str:  # pragma: no cover - mirrors message for logging
         return self.message
+
+
+@dataclass(eq=False)
+class ProfitabilityValidationError(Exception):
+    """Raised when profitability calculation inputs fail domain validation."""
+
+    message: str
+    field_errors: Sequence[str] | None = None
+
+    def __str__(self) -> str:  # pragma: no cover - mirrors message for logging
+        return self.message