fix: measure a window resize on web once for every provider

[YevheniiKotyrlo]

Summary

On web, every SafeAreaProvider measures a window resize from a resize listener of its own, and React commits the updates made in each listener separately, so nested providers commit once each per resize step. Each provider's ResizeObserver then measures again after layout and reports the values its listener already reported, which React renders once more. Two nested providers, as an Expo Router app mounts them beside an app shell's own provider, commit three times per step.

One resize listener now measures every provider, so React commits their updates together, and a provider reports only metrics that changed, as the Android and iOS providers do, so the observer callback that follows a resize commits nothing. The measurement stays in the resize event, so a provider that only moves is still measured and the new metrics still paint in the resize's own frame.

Test Plan

• NativeSafeAreaProvider.web-test.tsx: "measures nested providers from one window resize listener" and "does not report metrics that did not change" fail on main and pass here. "measures a window resize that moves the provider without resizing it" and "reports a window resize that changes the insets and leaves the frame as it was" hold the resize-event measurement for a provider that only moves and for an insets-only change.
• With two nested providers, a 190-step window resize drops from 570 React commits to 191 in Chromium, Firefox and WebKit, and both builds paint every step's new metrics in its own frame (measurements).
• The JS job passes on Ubuntu (Node 22.13.0, npm 10.9.2, JDK 17 for format:spotless:check).

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[YevheniiKotyrlo]

Measurements — before / after

UNFIXED — Over a 190-step window resize, two nested providers commit React 570 times, three per step: once in each provider's resize listener, and once more in the next frame, when their ResizeObservers report the values the listeners already reported.

FIXED — 191 commits, one per step and one more, from a single window resize listener.

	React commits	window resize listeners	steps painting their new metrics in the resize's own frame
before — stock 5.10.1	570	2	190 of 190
after — with this PR	191	1	190 of 190

Chromium 153, Firefox 155 and WebKit 26.6, two runs each, read the same. Two nested SafeAreaProviders on react-native-web, as an Expo Router app mounts them beside an app shell's own provider, narrowed from 1280 to 520 px in 4 px steps; the harness builds both from the library's source and checks each page's resize listeners against the build it claims. Chromium counts 570 layouts over the sweep for both builds.