Merge handle_control_event and persist_event_if_needed

The split existed only so handle_control_event could log
UnitStateChanged and then delegate; that's no longer worth its own
function. Co-locating the UnitStateChanged special case with the other
match arms makes its 'log-only, no persist' treatment self-evident,
and the call chain drops from handle → persist → record to handle →
record.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

crates/app_feeder_distributor/src/event.rs

@@ -105,28 +105,7 @@ async fn handle_control_event(
     ws_manager: Option<&Arc<WebSocketManager>>,
     metadata: &MetadataCache,
 ) {
-    // UnitStateChanged is high-frequency and intentionally not persisted;
+    let record: Option<EventInsert> = match &event {
-    // it still needs tracing for local observability. All other events are
-    // persisted via record_event, which emits tracing automatically.
-    if let AppEvent::UnitStateChanged {
-        unit_id,
-        from_state,
-        to_state,
-    } = &event
-    {
-        tracing::info!("Unit {} state: {} -> {}", unit_id, from_state, to_state);
-    }
-
-    persist_event_if_needed(&event, pool, ws_manager, metadata).await;
-}
-
-async fn persist_event_if_needed(
-    event: &AppEvent,
-    pool: &sqlx::PgPool,
-    ws_manager: Option<&Arc<WebSocketManager>>,
-    metadata: &MetadataCache,
-) {
-    let record: Option<EventInsert> = match event {
         AppEvent::EquipmentStartCommandSent {
             equipment_id,
             unit_id,
@@ -280,11 +259,18 @@ async fn persist_event_if_needed(
                 payload: serde_json::json!({ "unit_id": unit_id }),
             })
         }
-        AppEvent::UnitStateChanged { .. } => None,
+        // High-frequency, intentionally not persisted; tracing only for local observability.
+        AppEvent::UnitStateChanged {
+            unit_id,
+            from_state,
+            to_state,
+        } => {
+            tracing::info!("Unit {} state: {} -> {}", unit_id, from_state, to_state);
+            None
+        }
     };
 
-    let Some(record) = record else {
+    if let Some(record) = record {
-        return;
-    };
         record_event(pool, ws_manager.map(Arc::as_ref), record).await;
     }
+}