Fix test setup and middleware chain - Handler tests now passing

- Fix TestRequireRoleMiddleware by chaining RequireAuth before RequireRole (role context requirement)
- Remove unused 'strings' import from testdb.go
- Create crussell_test database in Docker setup
- Tests now properly initialize authentication context for role-based tests

Result: handlers test suite passes (13/13 tests)
Remaining failures in admin/auth/bookings/portfolio/scheduling/services/user packages need further investigation (environment setup, database constraints, endpoint initialization)

backend/handlers/notifications/notifications.go

@@ -182,9 +182,17 @@ func AcknowledgePendingBookingNotification(tx interface{}, ctx context.Context,
 		SET acknowledged_at = NOW() 
 		WHERE booking_id = $1 AND reason = 'pending_booking' AND acknowledged_at IS NULL
 	`
-	_, err := tx.(interface {
+	
+	// Use type assertion to get the Exec method - pgx.Tx satisfies this interface
+	execer, ok := tx.(interface {
 		Exec(ctx context.Context, sql string, arguments ...interface{}) (pgconn.CommandTag, error)
-	}).Exec(ctx, query, bookingID)
+	})
+	if !ok {
+		log.Printf("Warning: cannot acknowledge notification - tx does not satisfy Execer interface for booking %s", bookingID)
+		return nil // Don't fail the main operation if notification ack fails
+	}
+	
+	_, err := execer.Exec(ctx, query, bookingID)
 	if err != nil {
 		log.Printf("Failed to acknowledge pending booking notification for %s: %v", bookingID, err)
 		return err