docs: 移动蓝绿部署指南到 troubleshooting 目录

backend/alembic/versions/042_add_employee_avatar_updated_at.py

@@ -0,0 +1,31 @@
+"""add employee avatar_updated_at field for avatar refresh tracking
+
+Revision ID: 042_add_employee_avatar_updated_at
+Revises: 041_message_server_timestamp
+Create Date: 2026-07-05
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '042_add_employee_avatar_updated_at'
+down_revision: Union[str, None] = '041_message_server_timestamp'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # Add avatar_updated_at field to employees table
+    # This field tracks when the avatar was last updated from WeCom API
+    op.add_column(
+        'employees',
+        sa.Column('avatar_updated_at', sa.DateTime(), nullable=True, comment='头像最后更新时间')
+    )
+
+
+def downgrade() -> None:
+    op.drop_column('employees', 'avatar_updated_at')