feat(vitalsharing): close button on overlay + rename settings button

- Settings tab button renamed from "Open Overlay" to "Toggle Overlay"
  since the same button now closes the overlay if it's already open
  (it already toggled, the old label was misleading).
- Overlay now draws a red X close button in the top-right corner while
  Ctrl is held, matching UB's NetworkUI affordance. Ctrl+left-click on
  the X hides the overlay. Same Ctrl-modifier gate as the drag
  operation so the normal game UI is not affected.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

MosswartMassacre/ViewXML/mainViewTabbed.xml

@@ -40,7 +40,7 @@
 
         <!-- Vital sharing setting -->
         <control progid="DecalControls.Checkbox" name="chkVitalSharingEnabled" left="20" top="110" width="200" height="20" text="Vital Sharing (cross-PC)" checked="false"/>
-        <control progid="DecalControls.PushButton" name="btnVitalSharingOverlay" left="220" top="108" width="100" height="22" text="Open Overlay"/>
+        <control progid="DecalControls.PushButton" name="btnVitalSharingOverlay" left="220" top="108" width="100" height="22" text="Toggle Overlay"/>
 
         <!-- Verbose logging -->
         <control progid="DecalControls.Checkbox" name="chkVerboseLogging" left="20" top="230" width="300" height="20" text="Verbose logging (vital sharing / VTank feed)" checked="false"/>

MosswartMassacre/Views/VitalSharingOverlayView.cs

@@ -166,12 +166,28 @@ namespace MosswartMassacre.Views
         private const int WM_LBUTTONUP = 0x0202;
         private const int VK_CONTROL = 0x11;
 
+        private const int CLOSE_BTN_SIZE = 14;
+
         private static Rectangle HudRect()
         {
             if (_hud == null) return Rectangle.Empty;
             return new Rectangle(_hud.Location.X, _hud.Location.Y, HUD_WIDTH, Math.Max(1, _lastRowCount) * ROW_SIZE + 5);
         }
 
+        /// <summary>Hud-local rect for the close button (only used while Ctrl is held).</summary>
+        private static Rectangle CloseBtnRectLocal()
+        {
+            return new Rectangle(HUD_WIDTH - CLOSE_BTN_SIZE - 2, 2, CLOSE_BTN_SIZE, CLOSE_BTN_SIZE);
+        }
+
+        /// <summary>Screen-space rect for the close button at the current HUD location.</summary>
+        private static Rectangle CloseBtnRectScreen()
+        {
+            if (_hud == null) return Rectangle.Empty;
+            var local = CloseBtnRectLocal();
+            return new Rectangle(_hud.Location.X + local.X, _hud.Location.Y + local.Y, local.Width, local.Height);
+        }
+
         private static void OnWindowMessage(object sender, WindowMessageEventArgs e)
         {
             try
@@ -199,6 +215,13 @@ namespace MosswartMassacre.Views
                 switch (e.Msg)
                 {
                     case WM_LBUTTONDOWN:
+                        // Ctrl+click the close button in the top-right corner to close.
+                        if (CloseBtnRectScreen().Contains(mouse))
+                        {
+                            e.Eat = true;
+                            Hide();
+                            break;
+                        }
                         if (HudRect().Contains(mouse))
                         {
                             _isDragging = true;
@@ -306,7 +329,7 @@ namespace MosswartMassacre.Views
                         offset += ROW_SIZE;
                     }
 
-                    // Drag-highlight border when Ctrl is held
+                    // Drag-highlight border + close button when Ctrl is held
                     if (_isHoldingControl)
                     {
                         var w = HUD_WIDTH;
@@ -315,6 +338,19 @@ namespace MosswartMassacre.Views
                         tex.DrawLine(new PointF(w - 1, 0), new PointF(w - 1, h - 1), COLOR_DRAG_BORDER, 1);
                         tex.DrawLine(new PointF(w - 1, h - 1), new PointF(0, h - 1), COLOR_DRAG_BORDER, 1);
                         tex.DrawLine(new PointF(0, h - 1), new PointF(0, 0), COLOR_DRAG_BORDER, 1);
+
+                        // Close button: red box with a white X (top-right corner)
+                        var btn = CloseBtnRectLocal();
+                        tex.Fill(btn, Color.FromArgb(220, 160, 20, 20));
+                        tex.DrawLine(new PointF(btn.Left, btn.Top), new PointF(btn.Right - 1, btn.Top), Color.White, 1);
+                        tex.DrawLine(new PointF(btn.Right - 1, btn.Top), new PointF(btn.Right - 1, btn.Bottom - 1), Color.White, 1);
+                        tex.DrawLine(new PointF(btn.Right - 1, btn.Bottom - 1), new PointF(btn.Left, btn.Bottom - 1), Color.White, 1);
+                        tex.DrawLine(new PointF(btn.Left, btn.Bottom - 1), new PointF(btn.Left, btn.Top), Color.White, 1);
+                        // X glyph
+                        tex.DrawLine(new PointF(btn.Left + 3, btn.Top + 3),
+                                     new PointF(btn.Right - 4, btn.Bottom - 4), Color.White, 2);
+                        tex.DrawLine(new PointF(btn.Right - 4, btn.Top + 3),
+                                     new PointF(btn.Left + 3, btn.Bottom - 4), Color.White, 2);
                     }
 
                     // Text passes