fix: 政策列表增加public_only过滤，与详情接口保持一致

根因: 政策列表接口未传public_only=True，返回了is_public=false的政策；
详情接口要求is_public=True，导致点击政策详情返回404'政策不存在或已下架'。

修复: /opc/policy 接口增加public_only=True，并对媒体字段调用_resolve_content_media

app/api/routers/rbac_opc.py

@@ -118,7 +118,8 @@ async def opc_policy(
     db: Database = Depends(get_db),
     _u: dict = Depends(require_roles("opc_member")),
 ):
-    return {"items": await db.content.list(ctype="policy", status="published", scheduled_ready=True)}
+    items = await db.content.list(ctype="policy", status="published", public_only=True, scheduled_ready=True)
+    return {"items": [_resolve_content_media(it) for it in items]}
 
 
 def _resolve_content_media(item: dict) -> dict: