fix source-aware download tracking and filter/path regressions

Make download dedupe source-specific to prevent cross-provider ID collisions. Also correct non-remaster filtering, avoid FLAC tagging on non-FLAC files, and use album IDs for singles folder templating.

internal/app/app_test.go

@@ -189,7 +189,7 @@ func TestTrackRipPipeline(t *testing.T) {
 		t.Fatalf("expected downloaded file: %v", err)
 	}
 
-	ok, err := sqlite.IsDownloaded(ctx, "19512574")
+	ok, err := sqlite.IsDownloaded(ctx, "qobuz", "19512574")
 	if err != nil {
 		t.Fatalf("IsDownloaded() error = %v", err)
 	}
@@ -316,3 +316,44 @@ func TestApplyQobuzArtistFiltersRepeats(t *testing.T) {
 		t.Fatalf("unexpected winners: %+v", ids)
 	}
 }
+
+func TestApplyQobuzArtistFiltersNonRemaster(t *testing.T) {
+	albums := []collectionAlbum{
+		{ID: "rm", Title: "Album X (Remastered)"},
+		{ID: "orig", Title: "Album X"},
+	}
+
+	filtered := applyQobuzArtistFilters("artist", albums, config.QobuzDiscographyFilterConfig{NonRemaster: true})
+	if len(filtered) != 1 {
+		t.Fatalf("len(filtered)=%d want 1", len(filtered))
+	}
+	if filtered[0].ID != "orig" {
+		t.Fatalf("unexpected album kept: %+v", filtered[0])
+	}
+}
+
+func TestTrackOutputPathSinglesUsesAlbumID(t *testing.T) {
+	tmp := t.TempDir()
+	d := config.DefaultConfigData()
+	d.Downloads.Folder = tmp
+	d.Downloads.SourceSubdirectories = false
+	d.Filepaths.AddSinglesToFolder = true
+	d.Filepaths.FolderFormat = "{id}"
+	d.Filepaths.TrackFormat = "{title}"
+	d.Filepaths.RestrictCharacters = false
+
+	m := &Main{Config: &config.Config{File: d, Session: d}}
+	meta := map[string]any{
+		"album": map[string]any{
+			"id":     "album-123",
+			"title":  "Album",
+			"artist": map[string]any{"name": "Artist"},
+		},
+		"performer": map[string]any{"name": "Artist"},
+	}
+
+	out := m.trackOutputPath("qobuz", "track-999", "Song", "flac", meta, "", 0)
+	if got, want := filepath.Dir(out), filepath.Join(tmp, "album-123"); got != want {
+		t.Fatalf("trackOutputPath() dir=%q want %q", got, want)
+	}
+}