fix: 修复任务栏固定和右键菜单图标不显示问题

MainForm.cs

@@ -133,13 +133,20 @@ namespace TimerApp
             try
             {
                 // Generate and set custom icon
-                Icon icon = IconGenerator.GenerateClockIcon();
+                Icon icon = IconGenerator.GenerateClockIcon(64);
                 this.Icon = icon;
                 notifyIcon1.Icon = icon;
+
+                contextMenuStrip1.ShowImageMargin = true;
+                toolStripMenuItemShow.Image = null;
+                toolStripMenuItemExit.Image = null;
             }
             catch
             {
                  notifyIcon1.Icon = SystemIcons.Application;
+                 contextMenuStrip1.ShowImageMargin = true;
+                 toolStripMenuItemShow.Image = null;
+                 toolStripMenuItemExit.Image = null;
             }
 
             UpdateStatusUI();
@@ -541,6 +548,11 @@ namespace TimerApp
                     _hasShownMinimizeTip = true;
                 }
             }
+            else
+            {
+                notifyIcon1.Visible = false;
+                notifyIcon1.Dispose();
+            }
         }
 
         private void notifyIcon1_MouseDoubleClick(object sender, MouseEventArgs e)
@@ -564,6 +576,7 @@ namespace TimerApp
         {
             _monitor.Stop();
             notifyIcon1.Visible = false;
+            notifyIcon1.Dispose();
             Application.Exit();
         }