fix(R-1298): held-app reports only for installed apps (a restore hold always)

Red-proved. Commit only.

controller/cmd/controller/main.go

@@ -1068,6 +1068,12 @@ func main() {
 	// when one is gone, every hold again once a day and after each start. One observer of the hold store, so every
 	// writer is covered. Pinned by internal/holdreport.
 	holdReporter := holdreport.New(sett, notifier.PushEvent, logger)
+	// R-1298: „installed" = the app's app.yaml file exists (a product removal deletes it; an unreadable one still counts,
+	// the R-1220 rule). An install's hold of an app without one is not reported.
+	holdReporter.SetInstalled(func(stack string) bool {
+		_, err := os.Stat(filepath.Join(cfg.Paths.StacksDir, stack, "app.yaml"))
+		return err == nil
+	})
 	sched.Every("hold-report", time.Minute, func(ctx context.Context) error {
 		holdReporter.Tick(time.Now())
 		return nil