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/BatchUpload.razor

@@ -59,10 +59,7 @@
                 <InputFile OnChange="HandleSingleWavSelected" accept=".wav,audio/wav,audio/x-wav" disabled="@_uploading" />
                 @if (_tracks.Count > 0)
                 {
-                    <MudTextField @bind-Value="_tracks[0].TrackName"
-                                  Label="Track Name"
-                                  Variant="Variant.Outlined"
-                                  Disabled="_uploading" />
+                    @* Track name is derived from the Release Name for Session/Mix — no separate input. *@
                     <MudText Typo="Typo.caption">Selected: @(_tracks[0].WavFile?.Name ?? "—")</MudText>
                 }
             </MudStack>
@@ -247,6 +244,13 @@
             return;
         }
 
+        // For single-track media (Session/Mix) the track name is derived from the Release Name —
+        // no separate Track Name input is shown. Sync here so the stored name always matches.
+        if (MediumRules.CardinalityOf(_medium).IsSingleTrack && _tracks.Count > 0)
+        {
+            _tracks[0].TrackName = _albumName;
+        }
+
         _imagePath = null; // Clear any stale uploaded path from a prior partial attempt.
         _uploading = true;
         _uploadedCount = 0;