feat(p12-w2): track-cardinal high-res waveform fetch + bridge rewire

Add GET api/track/{trackEntryKey}/waveform/high-res (+ proxy), ITrackDataService.GetTrackWaveform; rewire visualizer to resolve the current track's EntryKey and re-fetch on track change. Retire the client mix-waveform read path.

DeepDrftPublic.Client/Services/IReleaseDataService.cs

@@ -24,11 +24,4 @@ public interface IReleaseDataService
 
     /// <summary>Single release resolved by its opaque public EntryKey, with both metadata satellites (nulls for non-matching media).</summary>
     Task<ApiResult<ReleaseDto>> GetByEntryKey(string entryKey);
-
-    /// <summary>
-    /// The Mix waveform datum for a release addressed by its public EntryKey. Success with a value
-    /// when present; success with a null value when no datum is stored (a valid state, not a failure);
-    /// failure on any other transport error.
-    /// </summary>
-    Task<ApiResult<WaveformProfileDto?>> GetMixWaveform(string entryKey);
 }