修复工作流表删除迁移幂等

backend/alembic/versions/20260116_05_remove_document_workflows.py

@@ -20,10 +20,18 @@ depends_on: Union[str, Sequence[str], None] = None
 
 
 def upgrade() -> None:
-    op.drop_table("workflow_actions")
-    op.drop_table("version_workflows")
-    op.drop_table("workflow_nodes")
-    op.drop_table("workflow_templates")
+    bind = op.get_bind()
+    inspector = sa.inspect(bind)
+    tables = set(inspector.get_table_names())
+
+    if "workflow_actions" in tables:
+        op.drop_table("workflow_actions")
+    if "version_workflows" in tables:
+        op.drop_table("version_workflows")
+    if "workflow_nodes" in tables:
+        op.drop_table("workflow_nodes")
+    if "workflow_templates" in tables:
+        op.drop_table("workflow_templates")
     op.execute("DROP TYPE IF EXISTS workflow_action_type")
     op.execute("DROP TYPE IF EXISTS workflow_status")