Fix ModuleNotFoundError for asyncpg by normalizing async DB URLs to psycopg2

Agent-Logs-Url: https://github.com/christianlouis/dmarq/sessions/d1890838-1770-4d5f-886f-f210df761fae

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

backend/app/core/database.py

@@ -1,4 +1,5 @@
 from typing import Generator
+from urllib.parse import urlparse, urlunparse
 
 from sqlalchemy import create_engine
 from sqlalchemy.ext.declarative import declarative_base
@@ -6,10 +7,33 @@ from sqlalchemy.orm import sessionmaker
 
 from app.core.config import get_settings
 
+_ASYNC_TO_SYNC_SCHEMES = {
+    "postgresql+asyncpg": "postgresql+psycopg2",
+}
+
+
+def _make_sync_db_url(url: str) -> str:
+    """Return the synchronous-driver equivalent of *url*.
+
+    Kubernetes and docker-compose deployments sometimes configure DATABASE_URL
+    with an async driver scheme (e.g. ``postgresql+asyncpg://``).  Alembic and
+    the synchronous SQLAlchemy engine used here require a sync driver, so we
+    map known async schemes to their psycopg2 equivalents.
+
+    Only the scheme component of the URL is rewritten; all other parts
+    (credentials, host, path, query) are left untouched.
+    """
+    parsed = urlparse(url)
+    sync_scheme = _ASYNC_TO_SYNC_SCHEMES.get(parsed.scheme)
+    if sync_scheme is None:
+        return url
+    return urlunparse(parsed._replace(scheme=sync_scheme))
+
+
 settings = get_settings()
 
-# Configure SQLAlchemy
-engine = create_engine(settings.DATABASE_URL, pool_pre_ping=True)
+# Configure SQLAlchemy (normalise async driver schemes to their sync equivalents)
+engine = create_engine(_make_sync_db_url(settings.DATABASE_URL), pool_pre_ping=True)
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 
 # Create base class for SQLAlchemy models