feat: add personal playlists and shareable track links

EOF

Co-authored-by: Cursor <cursoragent@cursor.com>

services/api/internal/playback/playlists_test.go

@@ -0,0 +1,21 @@
+package playback
+
+import (
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/require"
+	"strings"
+	"testing"
+)
+
+func TestValidatePlaylist(t *testing.T) {
+	id := uuid.New()
+	require.NoError(t, validatePlaylist("  В дорогу  ", "", []uuid.UUID{id}))
+	require.NoError(t, validatePlaylist(strings.Repeat("я", 120), strings.Repeat("я", 2000), nil))
+	for _, name := range []string{"", " \t\n", strings.Repeat("я", 121)} {
+		require.Error(t, validatePlaylist(name, "", nil))
+	}
+	require.Error(t, validatePlaylist("Mix", strings.Repeat("я", 2001), nil))
+	require.Error(t, validatePlaylist("Mix", "", []uuid.UUID{id, id}))
+	require.Error(t, validatePlaylist("Mix", "", []uuid.UUID{uuid.Nil}))
+	require.Error(t, validatePlaylist("Mix", "", make([]uuid.UUID, 2001)))
+}