Wire NowPlayingStats to live aggregates: add SQL track duration column, stats endpoint, and duration backfill

DeepDrftAPI/Controllers/TrackController.cs

@@ -173,6 +173,26 @@ public class TrackController : ControllerBase
         return Ok(status);
     }
 
+    // POST api/track/duration/backfill ([ApiKeyAuthorize], no body)
+    // One-time admin backfill: for every track whose SQL duration is still null, read the duration from
+    // the vault audio and write it to SQL. Mirrors the waveform backfill posture. Idempotent — a re-run
+    // only touches still-missing rows. Returns { updated, skipped }. Declared in the literal-route block
+    // (before "{trackId}") so the segment is never treated as a trackId.
+    [ApiKeyAuthorize]
+    [HttpPost("duration/backfill")]
+    public async Task<ActionResult> BackfillDurations(CancellationToken cancellationToken)
+    {
+        var result = await _unifiedService.BackfillDurationsAsync(cancellationToken);
+        if (!result.Success)
+        {
+            var error = result.Messages.FirstOrDefault()?.Message ?? "Unknown error";
+            _logger.LogError("BackfillDurations failed: {Error}", error);
+            return StatusCode(500, error);
+        }
+
+        return Ok(new { updated = result.Value.Updated, skipped = result.Value.Skipped });
+    }
+
     // POST api/track/upload: raw audio in (multipart/form-data) + metadata → persisted TrackDto out.
     // Accepts .wav, .mp3, and .flac. Used by the CMS upload flow on DeepDrftManager; that host
     // proxies the upload here so it never touches the vault disk path or SQL directly.