Bunch of improvements i dunno.

Wino.Core.Domain/MenuItems/MergedAccountMenuItem.cs

@@ -16,8 +16,39 @@ public partial class MergedAccountMenuItem : MenuItemBase<MergedInbox, IMenuItem
     [ObservableProperty]
     private int unreadItemCount;
 
+    /// <summary>
+    /// Total items to sync across all merged accounts.
+    /// </summary>
     [ObservableProperty]
-    private double synchronizationProgress;
+    [NotifyPropertyChangedFor(nameof(SynchronizationProgress))]
+    public partial int TotalItemsToSync { get; set; }
+
+    /// <summary>
+    /// Remaining items to sync across all merged accounts.
+    /// </summary>
+    [ObservableProperty]
+    [NotifyPropertyChangedFor(nameof(SynchronizationProgress))]
+    public partial int RemainingItemsToSync { get; set; }
+
+    /// <summary>
+    /// Current synchronization status message.
+    /// </summary>
+    [ObservableProperty]
+    public partial string SynchronizationStatus { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Calculated synchronization progress for merged accounts.
+    /// </summary>
+    public double SynchronizationProgress
+    {
+        get
+        {
+            if (TotalItemsToSync == 0 || RemainingItemsToSync == 0)
+                return -1; // Indeterminate
+
+            return ((double)(TotalItemsToSync - RemainingItemsToSync) / TotalItemsToSync) * 100;
+        }
+    }
 
     [ObservableProperty]
     private string mergedAccountName;
@@ -35,6 +66,20 @@ public partial class MergedAccountMenuItem : MenuItemBase<MergedInbox, IMenuItem
     {
         UnreadItemCount = SubMenuItems.OfType<IAccountMenuItem>().Sum(a => a.UnreadItemCount);
     }
+    
+    /// <summary>
+    /// Aggregates synchronization progress from all child account menu items.
+    /// </summary>
+    public void RefreshSynchronizationProgress()
+    {
+        var accountMenuItems = SubMenuItems.OfType<IAccountMenuItem>().ToList();
+        
+        TotalItemsToSync = accountMenuItems.Sum(a => a.TotalItemsToSync);
+        RemainingItemsToSync = accountMenuItems.Sum(a => a.RemainingItemsToSync);
+        
+        // Use first non-empty status message
+        SynchronizationStatus = accountMenuItems.FirstOrDefault(a => !string.IsNullOrEmpty(a.SynchronizationStatus))?.SynchronizationStatus ?? string.Empty;
+    }
 
     public void UpdateAccount(MailAccount account)
     {