feat(post): add nullable description + attachment_count (migration 0007)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

alembic/versions/0007_fc2d_post_metadata_fields.py

@@ -0,0 +1,31 @@
+"""fc2d-iv: post.description + post.attachment_count
+
+Revision ID: 0007
+Revises: 0006
+Create Date: 2026-05-18
+
+"""
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "0007"
+down_revision: Union[str, None] = "0006"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "post", sa.Column("description", sa.Text(), nullable=True)
+    )
+    op.add_column(
+        "post",
+        sa.Column("attachment_count", sa.Integer(), nullable=True),
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("post", "attachment_count")
+    op.drop_column("post", "description")