[iOS] SafeArea: Skip initial connection invalidation (#37841)

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## Description

Skips `InvalidateMeasure` from the iOS/Mac Catalyst `SafeAreaEdges`
mapper while a new handler is connecting. The initial layout pass
already reads the current safe-area value.

Reconnects and dynamic `SafeAreaEdges` changes retain the existing
invalidation behavior.

## Benchmark

The local Sandbox harness is not included in this PR. Release iOS
simulator, iPhone 16 Pro / iOS 18.4:

| Metric | Result |
|---|---:|
| Heavy tile `ToPlatform` (55 elements) | 12.841 ms |
| Flat tile `ToPlatform` (14 elements) | 4.735 ms |
| `SafeAreaEdges` mapper calls | 480 |
| `SafeAreaEdges` mapper total | <0.3 ms |

The attribution count includes mapper entries that return immediately.
This micro-optimization is below end-to-end simulator noise and no
aggregate speedup is claimed. The run completed all 70 benchmark results
with `run-end|ok`.

## Review

Independent GPT, Claude, and Gemini reviews traced the exact
`Connecting` / `Reconnecting` state flags, initial parent attachment,
non-default values, dynamic updates, and iOS/Mac Catalyst layout-time
safe-area reads. All three found the initial invalidation redundant and
the guard safe.

Copilot-Session: 5a03e13d-1a41-4652-a8c6-099eeb79cd50

Author: StephaneDelcroix

src/Core/src/Handlers/View/ViewHandler.iOS.cs

@@ -154,6 +154,11 @@ internal static void UpdateTransformation(IViewHandler handler, IView view)
 
 		internal static void MapSafeAreaEdges(IViewHandler handler, IView view)
 		{
+			if (handler.IsConnectingHandler())
+			{
+				return;
+			}
+
 			view.InvalidateMeasure();
 		}
 	}