Retry database readiness in live smoke

scripts/live_migration_smoke.sh

@@ -20,13 +20,26 @@ cd /app
 echo "Database URL is read from backend container settings / DATABASE_URL."
 
 python - <<'PY'
+import time
+
 from sqlalchemy import text
+from sqlalchemy.exc import OperationalError
 
 from app.db.session import get_engine
 
+last_error = None
+for attempt in range(1, 61):
+    try:
         with get_engine().connect() as connection:
             connection.execute(text("SELECT 1"))
-    print("Database connection: ok")
+            print(f"Database connection: ok after attempt {attempt}")
+            break
+    except OperationalError as exc:
+        last_error = exc
+        print(f"Database not ready yet ({attempt}/60): {exc}")
+        time.sleep(2)
+else:
+    raise SystemExit(f"Database did not become ready: {last_error}")
 PY
 
 python -m alembic upgrade head
@@ -113,13 +126,26 @@ echo "Using Python: $PYTHON_BIN"
 echo "Database URL is read from backend settings / DATABASE_URL."
 
 "$PYTHON_BIN" - <<'PY'
+import time
+
 from sqlalchemy import text
+from sqlalchemy.exc import OperationalError
 
 from app.db.session import get_engine
 
+last_error = None
+for attempt in range(1, 61):
+    try:
         with get_engine().connect() as connection:
             connection.execute(text("SELECT 1"))
-    print("Database connection: ok")
+            print(f"Database connection: ok after attempt {attempt}")
+            break
+    except OperationalError as exc:
+        last_error = exc
+        print(f"Database not ready yet ({attempt}/60): {exc}")
+        time.sleep(2)
+else:
+    raise SystemExit(f"Database did not become ready: {last_error}")
 PY
 
 "$PYTHON_BIN" -m alembic upgrade head