Fix duplicate instances remaining after update

Sources/Fluid/Services/SimpleUpdater.swift

@@ -918,6 +918,13 @@ final class SimpleUpdater {
                 DebugLogger.shared.info("SimpleUpdater: Successfully relaunched app, terminating old instance", source: "SimpleUpdater")
                 // Give the new instance time to fully start before terminating
                 DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) {
+                    // Arm the fallback watchdog BEFORE calling terminate, because terminate blocks.
+                    // The AppDelegate cleanup can take up to 16 seconds (8s for Private AI + 8s for ASR).
+                    // We wait 20 seconds on a background queue to ensure it only fires if truly hung.
+                    DispatchQueue.global().asyncAfter(deadline: .now() + 20.0) {
+                        exit(0)
+                    }
+
                     NSApp.terminate(nil)
                 }
             }