优化证书生成与正式部署配置

backend/alembic/versions/20260602_0002_project_defaults.py

@@ -23,8 +23,6 @@ def upgrade() -> None:
     op.execute("update project_courses set default_certificate_name='培训结业证书' where default_certificate_name is null")
     op.execute("update project_courses set default_course_name=name where default_course_name is null")
     op.execute("update project_courses set default_issuer_name='本公司' where default_issuer_name is null")
-    op.alter_column("project_courses", "default_certificate_name", nullable=False)
-    op.alter_column("project_courses", "default_issuer_name", nullable=False)
 
 
 def downgrade() -> None:

backend/alembic/versions/20260609_0003_add_pdf_last_accessed_at.py

@@ -0,0 +1,30 @@
+"""add pdf_last_accessed_at
+
+Revision ID: 20260609_0003
+Revises: 20260602_0002
+Create Date: 2026-06-09 00:00:00.000000
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '20260609_0003'
+down_revision: Union[str, None] = '20260602_0002'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.add_column('certificates', sa.Column('pdf_last_accessed_at', sa.DateTime(), nullable=True))
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_column('certificates', 'pdf_last_accessed_at')
+    # ### end Alembic commands ###