feat: Stream Now instant-play of a random track from the nav button

DeepDrftAPI/Controllers/TrackController.cs

@@ -72,6 +72,30 @@ public class TrackController : ControllerBase
         return Ok(result.Value);
     }
 
+    // GET api/track/random (unauthenticated)
+    // Picks one track at random from the full library and returns its metadata. Public, same auth
+    // posture as GET api/track/page. Selection math lives in the SQL service/repository, not here.
+    // 404 when the library is empty (a valid state the client renders as "no tracks yet"), 200 +
+    // TrackDto otherwise. Literal segment, declared before "{trackId}" so it never routes there.
+    [HttpGet("random")]
+    public async Task<ActionResult> GetRandom(CancellationToken cancellationToken = default)
+    {
+        var result = await _sqlTrackService.GetRandom(cancellationToken);
+        if (!result.Success)
+        {
+            var error = result.Messages.FirstOrDefault()?.Message ?? "Unknown error";
+            _logger.LogError("GetRandom failed: {Error}", error);
+            return StatusCode(500, "Failed to load track");
+        }
+
+        if (result.Value is null)
+        {
+            return NotFound();
+        }
+
+        return Ok(result.Value);
+    }
+
     // GET api/track/waveform-status ([ApiKeyAuthorize])
     // Admin backfill view: returns every track with a flag for whether a waveform profile is
     // stored in the WaveformProfiles vault. The catalogue is small enough that the CMS panel reads