feat: enhance project and scenario management with role-based access control

- Implemented role-based access control for project and scenario routes.
- Added authorization checks to ensure users have appropriate roles for viewing and managing projects and scenarios.
- Introduced utility functions for ensuring project and scenario access based on user roles.
- Refactored project and scenario routes to utilize new authorization helpers.
- Created initial data seeding script to set up default roles and an admin user.
- Added tests for authorization helpers and initial data seeding functionality.
- Updated exception handling to include authorization errors.

services/repositories.py

@@ -57,6 +57,10 @@ class ProjectRepository:
             raise EntityNotFoundError(f"Project {project_id} not found")
         return project
 
+    def exists(self, project_id: int) -> bool:
+        stmt = select(Project.id).where(Project.id == project_id).limit(1)
+        return self.session.execute(stmt).scalar_one_or_none() is not None
+
     def create(self, project: Project) -> Project:
         self.session.add(project)
         try:
@@ -133,6 +137,10 @@ class ScenarioRepository:
             raise EntityNotFoundError(f"Scenario {scenario_id} not found")
         return scenario
 
+    def exists(self, scenario_id: int) -> bool:
+        stmt = select(Scenario.id).where(Scenario.id == scenario_id).limit(1)
+        return self.session.execute(stmt).scalar_one_or_none() is not None
+
     def create(self, scenario: Scenario) -> Scenario:
         self.session.add(scenario)
         try: