Implement Alembic for database migrations and update FastAPI initialization

- Integrate Alembic for managing database schema migrations, replacing the previous SQL schema management.
- Update the FastAPI application to synchronize interface definitions at startup.
- Modify the Docker Compose command to run Alembic migrations before starting the API.
- Enhance the Makefile with new commands for database migration and revision management.
- Remove outdated SQL schema and seed files, transitioning to a more dynamic migration approach.
- Add initial migration scripts and configuration for Alembic, ensuring a structured database evolution.

backend/migrations/README

@@ -0,0 +1,5 @@
+Alembic migrations for the backend database.
+
+Run from backend/:
+
+    alembic upgrade head