8.L: collapse release/track name for single-track media (Session, Mix)

BatchTrackDetail gains ShowTrackName parameter (default true); BatchUpload removes the
Track Name input on the single-track path; BatchEdit suppresses it there too. Both sync
_tracks[0].TrackName = _albumName on submit/save so names can never diverge. Cut path
unchanged.

DeepDrftManager/Components/Pages/Tracks/BatchEdit.razor

@@ -72,6 +72,7 @@
                 <MudPaper Class="pa-4" Elevation="2">
                     <BatchTrackDetail SelectedTrack="@(_selectedIndex >= 0 && _tracks.Count > 0 ? _tracks[_selectedIndex] : null)"
                                       Disabled="_saving"
+                                      ShowTrackName="@(!MediumRules.CardinalityOf(_medium).IsSingleTrack)"
                                       TrackNameChanged="@(name => { if (_selectedIndex >= 0) { _tracks[_selectedIndex].TrackName = name; } })" />
                 </MudPaper>
             </MudItem>
@@ -337,6 +338,14 @@
         var album = string.IsNullOrWhiteSpace(_albumName) ? null : _albumName;
         var genre = string.IsNullOrWhiteSpace(_genre) ? null : _genre;
 
+        // For single-track media (Session/Mix) the track name is derived from the Release Name —
+        // no separate Track Name editor is shown. Sync here so changes to the Release Name always
+        // carry through to the stored track name.
+        if (MediumRules.CardinalityOf(_medium).IsSingleTrack && _tracks.Count > 0)
+        {
+            _tracks[0].TrackName = _albumName;
+        }
+
         _imagePath = null; // Clear any stale uploaded path from a prior partial attempt.
         _saving = true;
         _processedCount = 0;