fix: address code review findings

cmd/naviwatcher/main.go

@@ -97,8 +97,8 @@ func (a *App) Close() {
 func (a *App) run(ctx context.Context) error {
 	// Compute-only scanner hook: scan all monitored artists for missing
 	// releases and log the count. Notifier/Web UI are out of scope for this
-	// plan, so results are only logged. This call is non-blocking and
-	// goroutine-safe; it observes ctx cancellation and returns early.
+	// plan, so results are only logged. ScanAll is a blocking DB walk over
+	// every monitored artist; it observes ctx cancellation and returns early.
 	missing, err := scanner.ScanAll(ctx, a.db, a.cfg.Scanner.FuzzyThreshold)
 	if err != nil {
 		if ctx.Err() != nil {