feat(db): 迁移里的数据库角色名改为环境变量注入

backend/alembic/versions/0001_init.py

@@ -12,13 +12,13 @@ import sqlalchemy as sa
 from alembic import op
 from sqlalchemy.dialects import postgresql
 
+from app.roles import APP_ROLE, OWNER_ROLE
+
 revision: str = "0001"
 down_revision: str | None = None
 branch_labels: str | Sequence[str] | None = None
 depends_on: str | Sequence[str] | None = None
 
-APP_ROLE = "dadao_app"
-
 # 说明：asyncpg 走"预备语句"执行，**一条 execute 里只能有一条 SQL**，
 # 多条语句会报 `cannot insert multiple commands into a prepared statement`。
 # 所以这里按语句拆成元组，逐条执行。
@@ -76,7 +76,7 @@ POLICY_STATEMENTS: tuple[str, ...] = (
         f"workspace, app_user, member, invitation, audit_log TO {APP_ROLE};"
     ),
     (
-        "ALTER DEFAULT PRIVILEGES FOR ROLE dadao_owner IN SCHEMA public "
+        f"ALTER DEFAULT PRIVILEGES FOR ROLE {OWNER_ROLE} IN SCHEMA public "
         f"GRANT SELECT, INSERT, UPDATE, DELETE ON TABLES TO {APP_ROLE};"
     ),
 )