fix(vision): overlay wheel zoomを安定化

Tracker/Tracker.DebugHost/Components/Vision/VisionFieldCanvas.razor

@@ -48,6 +48,7 @@
              role="img"
              aria-label="SSL-Vision field"
              @onwheel="OnFieldWheel"
+             @onwheel:preventDefault="true"
              @onmousedown="OnFieldMouseDown"
              @onmousemove="OnFieldMouseMove"
              @onmouseup="OnFieldMouseUp"

Tracker/Tracker.DebugHost/Components/Vision/VisionFieldOverlayCanvas.razor

@@ -48,6 +48,7 @@
              role="img"
              aria-label="@AriaLabel"
              @onwheel="OnFieldWheel"
+             @onwheel:preventDefault="true"
              @onmousedown="OnFieldMouseDown"
              @onmousemove="OnFieldMouseMove"
              @onmouseup="OnFieldMouseUp"

Tracker/Tracker.Tests/VisionFieldRenderContractTests.cs

@@ -41,6 +41,19 @@ public void VisionFieldViewportState_AppliesDragWheelAndResetAsSingleState()
         Assert.False(state.IsDragging);
     }
 
+    /// <summary>
+    /// overlay field は split field と同じ wheel zoom / reset contract を持ち、wheel gesture を page scroll へ流さない。
+    /// </summary>
+    [Fact]
+    public void VisionFieldMarkup_OverlayAndSplitProvideDedicatedWheelZoom()
+    {
+        var splitMarkup = ReadRepositoryFile("Tracker/Tracker.DebugHost/Components/Vision/VisionFieldCanvas.razor");
+        var overlayMarkup = ReadRepositoryFile("Tracker/Tracker.DebugHost/Components/Vision/VisionFieldOverlayCanvas.razor");
+
+        AssertDedicatedWheelZoom(splitMarkup);
+        AssertDedicatedWheelZoom(overlayMarkup);
+    }
+
     /// <summary>
     /// split は split 用 component、overlay は overlay 用 component を別境界として使う。
     /// </summary>
@@ -79,6 +92,14 @@ public void DiagnosticsFieldMarkup_IsNotGatedOnlyByRenderSnapshot()
         Assert.DoesNotContain("@if (selectedRenderSnapshot is not null)", diagnosticsMarkup, StringComparison.Ordinal);
     }
 
+    private static void AssertDedicatedWheelZoom(string markup)
+    {
+        Assert.Contains("@onwheel=\"OnFieldWheel\"", markup, StringComparison.Ordinal);
+        Assert.Contains("@onwheel:preventDefault=\"true\"", markup, StringComparison.Ordinal);
+        Assert.Contains("@onclick=\"ResetFieldView\"", markup, StringComparison.Ordinal);
+        Assert.Contains("scale({N(viewport.Zoom)})", markup, StringComparison.Ordinal);
+    }
+
     private static string ExtractBetween(string text, string start, string end)
     {
         var startIndex = text.IndexOf(start, StringComparison.Ordinal);