Fix db override

Author: Maxteabag

sqlit/domains/connections/providers/bigquery/adapter.py

@@ -61,6 +61,12 @@ def supports_cross_database_queries(self) -> bool:
         # BigQuery supports cross-dataset queries
         return True
 
+    def apply_database_override(self, config: ConnectionConfig, database: str) -> ConnectionConfig:
+        """Apply a default dataset for unqualified queries."""
+        if not database:
+            return config
+        return config.with_endpoint(database=database)
+
     @property
     def system_databases(self) -> frozenset[str]:
         return frozenset({"INFORMATION_SCHEMA"})