feat: 定位模型重做、聚焦短显、托盘交互与 host spawn 修复

- 定位改为 水平(左/中/右) × 垂直(上/中/下) + 边缘留白，取代四角枚举
- 完成类通知在目标窗口已聚焦时用更短停留（FocusedDurationSeconds）
- 托盘左键单击直接打开设置，右键菜单仅保留退出
- 修复 host 拉起用 UseShellExecute=true，脱离钩子 stdout 管道，避免 Claude 卡在 running stop hook

Notify/ViewModels/SettingsViewModel.cs

@@ -18,7 +18,10 @@ public partial class SettingsViewModel : ObservableObject
 
         var s = settings.Current;
         DurationSeconds = s.DurationSeconds;
-        Corner = s.Corner;
+        FocusedDurationSeconds = s.FocusedDurationSeconds;
+        Horizontal = s.Horizontal;
+        Vertical = s.Vertical;
+        Margin = s.Margin;
         Opacity = s.Opacity;
         MaxVisible = s.MaxVisible;
         PlaySound = s.PlaySound;
@@ -27,14 +30,24 @@ public partial class SettingsViewModel : ObservableObject
         ShowOnAllDesktops = s.ShowOnAllDesktops;
     }
 
-    public IReadOnlyList<ToastCorner> Corners { get; } =
-        [ToastCorner.TopLeft, ToastCorner.TopRight, ToastCorner.BottomLeft, ToastCorner.BottomRight];
+    public IReadOnlyList<HEdge> Horizontals { get; } = [HEdge.Left, HEdge.Center, HEdge.Right];
+
+    public IReadOnlyList<VEdge> Verticals { get; } = [VEdge.Top, VEdge.Center, VEdge.Bottom];
 
     [ObservableProperty]
     public partial int DurationSeconds { get; set; }
 
     [ObservableProperty]
-    public partial ToastCorner Corner { get; set; }
+    public partial int FocusedDurationSeconds { get; set; }
+
+    [ObservableProperty]
+    public partial HEdge Horizontal { get; set; }
+
+    [ObservableProperty]
+    public partial VEdge Vertical { get; set; }
+
+    [ObservableProperty]
+    public partial int Margin { get; set; }
 
     [ObservableProperty]
     public partial double Opacity { get; set; }
@@ -63,7 +76,10 @@ public partial class SettingsViewModel : ObservableObject
         _settings.Save(new ToastSettings
         {
             DurationSeconds = DurationSeconds,
-            Corner = Corner,
+            FocusedDurationSeconds = FocusedDurationSeconds,
+            Horizontal = Horizontal,
+            Vertical = Vertical,
+            Margin = Margin,
             Opacity = Opacity,
             MaxVisible = MaxVisible,
             PlaySound = PlaySound,