fix: add #[must_use] to unread_count, collect_unread, unread_summary per codebase convention

hive-matrix-mcp/src/handlers.rs

@@ -349,6 +349,7 @@ pub async fn read_room(client: &Client, room_ref: &str, limit: Option<usize>) ->
 /// cached by the matrix-sdk client. Used by the harness to surface
 /// unread matrix activity in `get_loose_ends` without exposing
 /// message content.
+#[must_use]
 pub fn unread_count(client: &Client) -> DaemonResponse {
     let rooms = client
         .joined_rooms()
@@ -363,6 +364,7 @@ pub fn unread_count(client: &Client) -> DaemonResponse {
 /// one unread notification the last message body is fetched via the
 /// `/messages` endpoint (best-effort; failures leave `last_body` as
 /// `None`). Rooms with zero unreads are omitted.
+#[must_use]
 pub async fn collect_unread(client: &Client) -> Vec<crate::protocol::RoomUnread> {
     use crate::protocol::RoomUnread;
     let mut result = Vec::new();
@@ -423,6 +425,7 @@ async fn fetch_last_message(
 /// Return per-room unread summaries. For rooms with exactly one
 /// unread notification, attempts to include the sender + truncated
 /// body; rooms with multiple unreads carry only the count.
+#[must_use]
 pub async fn unread_summary(client: &Client) -> DaemonResponse {
     let rooms = collect_unread(client).await;
     DaemonResponse::ok(&rooms)