feat(content): 资讯详情 阅读数 + 留言

- 迁移0017：content_items.read_count + content_comments 表
- ContentRepository：_to_dict 加 read_count；incr_read_count/content_comments/add_content_comment
- rbac_opc：GET /opc/content/{id} 自增阅读数；GET/POST /opc/content/{id}/comments(发布需 opc_member，带昵称/头像)

Co-Authored-By: Claude <noreply@anthropic.com>

alembic/versions/0017_content_detail.py

@@ -0,0 +1,35 @@
+"""content read_count + content_comments
+
+Revision ID: 0017_content_detail
+Revises: 0016_content_media
+Create Date: 2026-08-27
+"""
+from __future__ import annotations
+
+import sqlalchemy as sa
+from alembic import op
+
+revision = "0017_content_detail"
+down_revision = "0016_content_media"
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    op.add_column("content_items", sa.Column("read_count", sa.Integer(), nullable=False, server_default="0"))
+    op.create_table(
+        "content_comments",
+        sa.Column("id", sa.String(), primary_key=True),
+        sa.Column("content_id", sa.String(), default="", index=True),
+        sa.Column("user_id", sa.String(), default=""),
+        sa.Column("username", sa.String(), default=""),
+        sa.Column("nickname", sa.String(), default=""),
+        sa.Column("avatar", sa.String(), default=""),
+        sa.Column("content", sa.Text(), default=""),
+        sa.Column("created_at", sa.String(), default=""),
+    )
+
+
+def downgrade() -> None:
+    op.drop_table("content_comments")
+    op.drop_column("content_items", "read_count")