Add endpoint to view all manual track mappings

- GET /api/admin/mappings/tracks returns all manual mappings
- Shows both Jellyfin (local) and external provider mappings
- Groups by playlist and includes creation timestamps
- Returns counts for jellyfin vs external mappings

allstarr/Controllers/AdminController.cs

@@ -2891,6 +2891,72 @@ public class AdminController : ControllerBase
         }
     }
     
+    /// <summary>
+    /// Get all manual track mappings (both Jellyfin and external) for all playlists
+    /// </summary>
+    [HttpGet("mappings/tracks")]
+    public async Task<IActionResult> GetAllTrackMappings()
+    {
+        try
+        {
+            var mappingsDir = "/app/cache/mappings";
+            var allMappings = new List<object>();
+            
+            if (!Directory.Exists(mappingsDir))
+            {
+                return Ok(new { mappings = allMappings, totalCount = 0 });
+            }
+            
+            var files = Directory.GetFiles(mappingsDir, "*_mappings.json");
+            
+            foreach (var file in files)
+            {
+                try
+                {
+                    var json = await System.IO.File.ReadAllTextAsync(file);
+                    var playlistMappings = JsonSerializer.Deserialize<Dictionary<string, ManualMappingEntry>>(json);
+                    
+                    if (playlistMappings != null)
+                    {
+                        var fileName = Path.GetFileNameWithoutExtension(file);
+                        var playlistName = fileName.Replace("_mappings", "").Replace("_", " ");
+                        
+                        foreach (var mapping in playlistMappings.Values)
+                        {
+                            allMappings.Add(new
+                            {
+                                playlist = playlistName,
+                                spotifyId = mapping.SpotifyId,
+                                type = !string.IsNullOrEmpty(mapping.JellyfinId) ? "jellyfin" : "external",
+                                jellyfinId = mapping.JellyfinId,
+                                externalProvider = mapping.ExternalProvider,
+                                externalId = mapping.ExternalId,
+                                createdAt = mapping.CreatedAt
+                            });
+                        }
+                    }
+                }
+                catch (Exception ex)
+                {
+                    _logger.LogWarning(ex, "Failed to read mapping file {File}", file);
+                }
+            }
+            
+            return Ok(new 
+            { 
+                mappings = allMappings.OrderBy(m => ((dynamic)m).playlist).ThenBy(m => ((dynamic)m).createdAt),
+                totalCount = allMappings.Count,
+                jellyfinCount = allMappings.Count(m => ((dynamic)m).type == "jellyfin"),
+                externalCount = allMappings.Count(m => ((dynamic)m).type == "external")
+            });
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Failed to get track mappings");
+            return StatusCode(500, new { error = "Failed to get track mappings" });
+        }
+    }
+    
     /// <summary>
     /// Test Spotify lyrics API by fetching lyrics for a specific Spotify track ID
     /// Example: GET /api/admin/lyrics/spotify/test?trackId=3yII7UwgLF6K5zW3xad3MP