fix: omit unsupported $top query option on chat members list

[amanjoshicodes]

Fixes #27.

teams chat members list <chat-id> failed with HTTP 400 because chats::list_members appended $top to GET /chats/{id}/members, which doesn't support OData query parameters. Microsoft Graph rejects the request with Query option 'Top' is not allowed.

This routes list_members through the existing GraphClient::get_paged_without_top — added in #24 for the same class of bug on list_channels — so the request pages via @odata.nextLink without $top.

Changes

• chats::list_members now delegates to a private list_members_at(url, ...) helper that calls get_paged_without_top, mirroring the list_channels / list_channels_at shape introduced in Fix channel list pagination query #24.
• Adds a wiremock unit test list_members_omits_top_query_parameter asserting the outgoing request carries no $top (matches the list_channels_omits_top_query_parameter test).

Verification

• cargo fmt --all, cargo clippy --all-targets -- -D warnings, cargo test --all-targets — all green (76 unit + 44 integration).
• Live against a real group chat: teams chat members list <chat-id> now returns members instead of a 400.

Scope is intentionally limited to chat members. Team members and channel members both document $top support, so they're unchanged.

[sionsmith]

Firstly thank you @amanjoshicodes - we will check this today / tomorrow 👍