Refactor database initialization and remove Alembic migrations

- Removed legacy Alembic migration files and consolidated schema management into a new Pydantic-backed initializer (`scripts/init_db.py`).
- Updated `main.py` to ensure the new DB initializer runs on startup, maintaining idempotency.
- Adjusted session management in `config/database.py` to prevent DetachedInstanceError.
- Introduced new enums in `models/enums.py` for better organization and clarity.
- Refactored various models to utilize the new enums, improving code maintainability.
- Enhanced middleware to handle JSON validation more robustly, ensuring non-JSON requests do not trigger JSON errors.
- Added tests for middleware and enums to ensure expected behavior and consistency.
- Updated changelog to reflect significant changes and improvements.

services/repositories.py

@@ -27,6 +27,11 @@ from services.export_query import ProjectExportFilters, ScenarioExportFilters
 from services.pricing import PricingMetadata
 
 
+def _enum_value(e):
+    """Return the underlying value for Enum members, otherwise return as-is."""
+    return getattr(e, "value", e)
+
+
 class ProjectRepository:
     """Persistence operations for Project entities."""
 
@@ -202,7 +207,9 @@ class ScenarioRepository:
         return self.session.execute(stmt).scalar_one()
 
     def count_by_status(self, status: ScenarioStatus) -> int:
-        stmt = select(func.count(Scenario.id)).where(Scenario.status == status)
+        status_val = _enum_value(status)
+        stmt = select(func.count(Scenario.id)).where(
+            Scenario.status == status_val)
         return self.session.execute(stmt).scalar_one()
 
     def recent(self, limit: int = 5, *, with_project: bool = False) -> Sequence[Scenario]:
@@ -219,9 +226,10 @@ class ScenarioRepository:
         limit: int | None = None,
         with_project: bool = False,
     ) -> Sequence[Scenario]:
+        status_val = _enum_value(status)
         stmt = (
             select(Scenario)
-            .where(Scenario.status == status)
+            .where(Scenario.status == status_val)
             .order_by(Scenario.updated_at.desc())
         )
         if with_project:
@@ -311,7 +319,11 @@ class ScenarioRepository:
                 stmt = stmt.where(Scenario.name.ilike(name_pattern))
 
             if filters.statuses:
-                stmt = stmt.where(Scenario.status.in_(filters.statuses))
+                # Accept Enum members or raw values in filters.statuses
+                status_values = [
+                    _enum_value(s) for s in (filters.statuses or [])
+                ]
+                stmt = stmt.where(Scenario.status.in_(status_values))
 
             if filters.start_date_from:
                 stmt = stmt.where(Scenario.start_date >=