fix(webicached): don't treat 0-asset packages as perpetually stale

Packages that produce no classifiable assets (e.g. mariadb-galera with
the galera asset_filter) were being refetched every batch because
!hasAssets marked them stale regardless of timestamp. The hasAssets
condition was intended for the startup case (classified from empty
rawcache), but those packages are already caught by t.IsZero() on first
run. Respect the timestamp for 0-asset results as for any other package.

cmd/webicached/main.go

@@ -332,14 +332,13 @@ func (wc *WebiCache) stalest(packages []pkgConf) []pkgConf {
 	for _, pkg := range packages {
 		data, err := wc.Store.Load(ctx, pkg.name)
 		var t time.Time
-		hasAssets := false
 		if err == nil && data != nil {
 			t = data.UpdatedAt
-			hasAssets = len(data.Assets) > 0
 		}
-		// Never fetched, or has no assets despite having a timestamp
+		// Never fetched, or older than 10 minutes.
-		// (e.g. classified from empty rawcache), or older than 10 minutes.
+		// 0-asset results are not treated as perpetually stale — packages that
-		if t.IsZero() || !hasAssets || time.Since(t) > 10*time.Minute {
+		// produce no classifiable assets (e.g. galera) respect the timestamp.
+		if t.IsZero() || time.Since(t) > 10*time.Minute {
 			stale = append(stale, stamped{pkg: pkg, updatedAt: t})
 		}
 	}