feat: add list loaded threads to app server

[jif-oai]

No description provided.

[owenlin0]

Should this return Vec<Thread>? i.e. would the metadata on Thread be useful?

We don't have to populate all the turns & items since we only do that for specific APIs (we've already documented the behavior on the Thread object)

[jif-oai]

No because sometimes we don't have them and don't need them

[owenlin0]

Also, would be nice to support pagination for consistency with our other list APIs, even though in practice you'd probably want to return everything always. Mainly because adding pagination later is a breaking change

pub struct ThreadLoadedListRequest {
    /// Opaque pagination cursor returned by a previous call.
    pub cursor: Option<String>,
    /// Optional page size; defaults to no limit
    pub limit: Option<u32>,
}

pub struct ThreadLoadedListResponse {
    pub data: Vec<String>,
    /// Opaque cursor to pass to the next call to continue after the last item.
    /// if None, there are no more items to return.
    pub next_cursor: Option<String>,
}