fix(migrations): support virtualenv Alembic execution

backend/alembic/env.py

@@ -1,10 +1,18 @@
 import asyncio
+import sys
 from logging.config import fileConfig
+from pathlib import Path
 from sqlalchemy import pool
 from sqlalchemy.engine import Connection
 from sqlalchemy.ext.asyncio import async_engine_from_config
 from alembic import context
 
+# Ensure Alembic works both in the container and when invoked from a virtualenv
+# on a server where the console-script directory would otherwise be sys.path[0].
+BACKEND_ROOT = Path(__file__).resolve().parents[1]
+if str(BACKEND_ROOT) not in sys.path:
+    sys.path.insert(0, str(BACKEND_ROOT))
+
 from app.database import Base
 from app.models import *  # noqa: import all models
 from app.config import settings