fix(plugin): allow real session.idle after synthetic idle within dedup window

When session.status(idle) is converted to synthetic session.idle and recorded in recentAnyIdles, a real session.idle arriving within 500ms was being dropped by the dedup logic. recentSyntheticIdles was cleared but recentAnyIdles persisted, causing TODO-DIAG to red-alert with 'no todossession.idle event'.

Fix: when real session.idle arrives, also clear recentAnyIdles entry so dedup does not drop it. Test renamed and expected dispatchCalls updated 1 → 2.

Fixes #2667

src/plugin/event.ts

@@ -415,6 +415,9 @@ export function createEventHandler(args: {
         const emittedAt = recentSyntheticIdles.get(sessionID);
         if (emittedAt !== undefined && now - emittedAt < DEDUP_WINDOW_MS) {
           recentSyntheticIdles.delete(sessionID);
+          // Let real idle events through even when a synthetic idle fired moments earlier.
+          // OpenCode diagnostics expect a concrete session.idle event signal.
+          recentAnyIdles.delete(sessionID);
         }
         recentRealIdles.set(sessionID, now);
         if (!shouldDispatchIdleEvent(sessionID, now)) {