fix: distinguish GetAllValidUserIds query failure from empty result GetAllValidUserIds now returns std::optional to separate a query failure (nullopt) from a genuinely empty user list. SecurityAgentImpl continues the SetActiveUser flow with an empty valid-user-id list on failure, so a transient OsAccount query failure is no longer conflated with "no valid users". Signed-off-by: Tianshi Liu <tianshi.liu@huawei.com> 🤖 AI[97%] 🔧 Human Fixed[0%] 🧑 Human[3%] 👌 AI Adopted[100%] Co-authored-by: claude (glm-5.2) <ai@local> Change-Id: I95e5f72fffe7731b6c338aa75503b930f5503904 |