feat(waveform): generalize high-res compute to every track (Direction B)

Per-track high-res datum keyed by EntryKey in the renamed track-waveforms vault; computed at upload for all tracks, regenerable per-track via CMS, with a re-runnable backfill. Mix read path repointed so it keeps working.

DeepDrftAPI/Services/UnifiedTrackService.cs

@@ -158,24 +158,38 @@ public class UnifiedTrackService
             return ResultContainer<TrackDto>.CreateFailResult($"Track was uploaded but could not be saved: {error}");
         }
 
-        // Best-effort waveform profile: both stores succeeded, so the upload is a success
-        // regardless of the profile outcome. A missing profile renders as a flat seekbar on the
+        // Best-effort waveform datums: both stores succeeded, so the upload is a success regardless of
+        // the datum outcome. A missing datum renders as a flat seekbar / blank visualizer on the
         // frontend, so a failure here is logged and swallowed — never fails the upload.
-        await TryStoreWaveformProfileAsync(tempFilePath, unpersisted.EntryKey, ct);
+        await TryStoreWaveformDatumsAsync(unpersisted.EntryKey, ct);
 
         return saveResult;
     }
 
-    private async Task TryStoreWaveformProfileAsync(string tempFilePath, string entryKey, CancellationToken ct)
+    // Compute and store both waveform datums for a freshly uploaded track: the fixed 512-bucket profile
+    // the player-bar seeker consumes, and the duration-derived high-res datum the lava visualizer
+    // consumes (phase-12 §5 — every track now carries one, computed at upload). Both source the same
+    // audio: read it back from the vault once (the authoritative parsed duration + the stored buffer)
+    // rather than re-reading and re-parsing the temp file. Best-effort throughout — never fails upload.
+    private async Task TryStoreWaveformDatumsAsync(string entryKey, CancellationToken ct)
     {
         try
         {
-            var wavBytes = await File.ReadAllBytesAsync(tempFilePath, ct);
-            await _waveformProfileService.ComputeAndStoreAsync(wavBytes, entryKey);
+            var audio = await _contentTrackContentService.GetAudioBinaryAsync(entryKey);
+            if (audio is null)
+            {
+                _logger.LogWarning(
+                    "Waveform datum step: no audio in vault for {EntryKey} immediately after store; skipping.",
+                    entryKey);
+                return;
+            }
+
+            await _waveformProfileService.ComputeAndStoreAsync(audio.Buffer, entryKey);
+            await _waveformProfileService.ComputeAndStoreHighResAsync(audio.Buffer, entryKey, audio.Duration);
         }
         catch (Exception ex) when (ex is not OperationCanceledException)
         {
-            _logger.LogError(ex, "Waveform profile step failed for {EntryKey}; upload unaffected.", entryKey);
+            _logger.LogError(ex, "Waveform datum step failed for {EntryKey}; upload unaffected.", entryKey);
         }
     }