Keep completed dashboard experiment available on demand

Author: jlucaso1

.github/workflows/prefetch-performance.yml

@@ -22,6 +22,7 @@ env:
 
 jobs:
   prefetch:
+    if: github.event_name == 'workflow_dispatch'
     name: Dashboard JSON (${{ matrix.mode }})
     runs-on: ubuntu-24.04
     timeout-minutes: 45

benches/dashboard_json.rs

@@ -3,6 +3,7 @@
 use std::collections::VecDeque;
 use whatsapp_rust::{serde, serde_json};
 
+#[allow(unused_imports)] // The imported production module contains host-only tests.
 #[path = "../consumer/src/supervisor/message_log.rs"]
 mod message_log;
 use message_log::MessageLogEntry;