Function search 

pub async fn search(
    memory: Option<&Arc<MemoryService>>,
    query: &str,
    user_ctx: &UserContext,
    agent_id: Option<&str>,
    session_id: Option<&str>,
    limit: usize,
    categories: Option<&[String]>,
) -> Result<Vec<Memory>>

Semantic search over a user’s memories.