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>

app/api/routers/rbac_opc.py

@@ -91,9 +91,8 @@ async def opc_policy(
 async def opc_content(
     type: str = "news",
     db: Database = Depends(get_db),
-    _u: dict = Depends(require_roles("opc_member")),
 ):
-    """C 端资讯：type ∈ policy(政策)/news(资讯)/skill(技能)/dynamic(动态)，仅 published。"""
+    """C 端资讯：type ∈ policy(政策)/news(资讯)/skill(技能)/dynamic(动态)，仅 published。公开浏览。"""
     return {"items": await db.content.list(ctype=type, status="published")}
 
 
@@ -101,14 +100,50 @@ async def opc_content(
 async def opc_content_detail(
     content_id: str,
     db: Database = Depends(get_db),
-    _u: dict = Depends(require_roles("opc_member")),
 ):
     item = await db.content.get(content_id)
     if item is None or item.get("status") != "published":
         raise HTTPException(status_code=404, detail="内容不存在")
+    # 阅读数自增（每次详情浏览 +1）
+    if item.get("status") == "published":
+        await db.content.incr_read_count(content_id)
+        item["read_count"] = (item.get("read_count") or 0) + 1
     return item
 
 
+@router.get("/content/{content_id}/comments", summary="资讯留言列表")
+async def opc_content_comments(
+    content_id: str,
+    db: Database = Depends(get_db),
+):
+    return {"items": await db.content.content_comments(content_id)}
+
+
+class ContentCommentBody(BaseModel):
+    content: str
+
+
+@router.post("/content/{content_id}/comments", summary="发表留言")
+async def opc_content_add_comment(
+    content_id: str,
+    body: ContentCommentBody,
+    db: Database = Depends(get_db),
+    user: dict = Depends(require_roles("opc_member")),
+):
+    if not body.content.strip():
+        raise HTTPException(status_code=400, detail="留言不能为空")
+    item = await db.content.get(content_id)
+    if item is None or item.get("status") != "published":
+        raise HTTPException(status_code=404, detail="内容不存在")
+    # 取当前用户资料（昵称/头像）用于留言展示
+    me = await db.users.get_by_id(user["id"]) or {}
+    actor = {"id": user["id"], "username": user.get("username", ""),
+             "nickname": (me.get("nickname") or user.get("username", "")),
+             "avatar": me.get("avatar", "")}
+    comment = await db.content.add_content_comment(content_id, actor, body.content.strip())
+    return {"ok": True, "comment": comment}
+
+
 @router.get("/finance", summary="财务流水")
 async def opc_finance(
     db: Database = Depends(get_db),