Fix large CMS upload timeout with idle heartbeat and add per-file progress meter

Replace the 100s default HttpClient timeout (set Timeout=Infinite) with an idle/heartbeat
deadline driven by a ProgressStreamContent wrapper that reports bytes-on-the-wire. Each tick
resets the idle window and advances a MudProgressLinear per upload row. Idle window is
configurable via Upload:IdleTimeoutSeconds (default 90s).

DeepDrftManager/Components/Pages/Tracks/BatchRowModel.cs

@@ -27,6 +27,17 @@ public class BatchRowModel
     public BatchRowStatus Status { get; set; } = BatchRowStatus.Queued;
 
     public string? ErrorMessage { get; set; }
+
+    /// <summary>Bytes pushed to the wire so far for this row's in-flight upload. Reset per attempt.</summary>
+    public long UploadedBytes { get; set; }
+
+    /// <summary>Total payload bytes for this row (the WAV file size), the progress denominator.</summary>
+    public long TotalBytes { get; set; }
+
+    /// <summary>Upload completion as a 0–100 percent, or 0 when the total is unknown.</summary>
+    public int UploadPercent => TotalBytes > 0
+        ? (int)Math.Clamp(UploadedBytes * 100 / TotalBytes, 0, 100)
+        : 0;
 }
 
 public enum BatchRowStatus { Queued, Uploading, Done, Failed }