hive-sh4re: delete now_unix(), the migration's last call sites are gone

hive-agent/src/turn.rs

@@ -416,7 +416,8 @@ fn maybe_auto_reset(bus: &Bus) {
     if last_ended == 0 {
         return; // no completed turn yet
     }
-    // Compute idle seconds using the same clock as now_unix (unix epoch, i64).
+    // Compute idle seconds using the same clock semantics as elsewhere
+    // in this crate (unix epoch, i64 seconds via `Utc::now().timestamp()`).
     let now = std::time::SystemTime::now()
         .duration_since(std::time::UNIX_EPOCH)
         .map_or(0, |d| d.as_secs());