fix(migrations): enforce schema ownership safety

server/src/app/db/schema_ownership.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+from sqlalchemy.engine import Connection, Engine
+
+from app.db.base import Base
+
+MIGRATION_OWNED_TABLES: frozenset[str] = frozenset(
+    {
+        "auth_sessions",
+        "expense_cases",
+        "expense_case_links",
+        "business_events",
+    }
+)
+
+
+def create_legacy_schema(bind: Engine | Connection) -> None:
+    """创建仍由旧 bootstrap 管理的表，不越过 Alembic 的表所有权边界。"""
+    legacy_tables = [
+        table for table in Base.metadata.sorted_tables if table.name not in MIGRATION_OWNED_TABLES
+    ]
+    Base.metadata.create_all(bind=bind, tables=legacy_tables)