feat：数据迁移脚本补充

backend/open_webui/migrations/versions/b2c3d4e5f6a7_fix_user_table_fields.py

@@ -0,0 +1,51 @@
+"""Add missing username field to user table
+
+Revision ID: b2c3d4e5f6a7
+Revises: a1b2c3d4e5f6
+Create Date: 2025-12-07 15:00:00.000000
+
+修复 user 表字段缺失问题：
+- 添加 username 字段 (String(50), nullable)
+
+问题来源：
+- username 字段在模型中存在但从未通过迁移添加
+"""
+
+from alembic import op
+import sqlalchemy as sa
+
+
+revision = "b2c3d4e5f6a7"
+down_revision = "a1b2c3d4e5f6"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    """升级数据库：添加 username 字段"""
+    from sqlalchemy import inspect
+
+    connection = op.get_bind()
+    inspector = inspect(connection)
+
+    # 获取 user 表的现有列
+    existing_columns = {col['name'] for col in inspector.get_columns('user')}
+
+    # 添加 username 字段（仅当不存在时）
+    if "username" not in existing_columns:
+        op.add_column("user", sa.Column("username", sa.String(50), nullable=True))
+
+
+def downgrade():
+    """降级数据库：删除 username 字段"""
+    from sqlalchemy import inspect
+
+    connection = op.get_bind()
+    inspector = inspect(connection)
+
+    # 获取 user 表的现有列
+    existing_columns = {col['name'] for col in inspector.get_columns('user')}
+
+    # 删除 username 字段（仅当存在时）
+    if "username" in existing_columns:
+        op.drop_column("user", "username")