fix(coverart/test): set MinInterval in rate-limit-serialization tests

internal/coverart/provider_lastfm_test.go

@@ -353,7 +353,23 @@ func TestLastfm_RateLimit_Serializes(t *testing.T) {
 	}))
 	defer srv.Close()
 
-	p := newLastfmTestProvider(t, srv.URL+"/", "test-key")
+	prevBase := lastfmBaseURL
+	lastfmBaseURL = srv.URL + "/"
+	t.Cleanup(func() { lastfmBaseURL = prevBase })
+
+	// Build a provider WITH the production MinInterval so this test can
+	// verify the rate-limit actually serializes. Other tests use
+	// newLastfmTestProvider which leaves MinInterval=0 for speed.
+	p := &lastfmProvider{client: newHTTPClient(httpClientOptions{
+		Name:                 "lastfm",
+		HTTPClient:           &http.Client{Timeout: 5 * time.Second},
+		MinInterval:          lastfmMinPeriod,
+		TreatAuthAsTransient: true,
+		BaseBackoff:          time.Millisecond,
+	})}
+	p.enabled.Store(true)
+	key := "test-key"
+	p.apiKey.Store(&key)
 
 	start := time.Now()
 	_, _, _ = p.FetchArtistArt(context.Background(), ArtistRef{Name: "A"})