[iOS] Ensure RCTScrollViewComponentView scroll view always matches its bounds

[davidecallegaro]

Summary

Fixes the "ScrollView content laid out but never drawn" failure on Fabric iOS: RCTScrollViewComponentView sizes its inner RCTEnhancedScrollView only via an autoresizing mask, and the scroll view is created at CGRectZero (initWithFrame:self.bounds at component-view creation time). Autoresizing propagates deltas only at the instant the parent's frame changes — if that moment is missed (observed reliably under heavy mount/teardown churn on thermally-throttled devices), the inner scroll view remains 0×0 forever: the shell carries its correct Yoga frame, onLayout/onContentSizeChange fire normally, the content subtree is fully mounted and laid out — and everything is clipped into a zero-size viewport.

This change enforces the invariant explicitly instead of relying on autoresizing alone: _ensureScrollViewMatchesBounds re-glues the scroll view to the shell's bounds in updateLayoutMetrics: and layoutSubviews. It adjusts bounds.size + center (not frame) so the RTL scale(-1, 1) transform is respected, and preserves bounds.origin, which for UIScrollView is the contentOffset. No-op when everything is healthy.

Diagnosis evidence (native view-hierarchy capture of a live occurrence, plus a setFrame: veto-swizzle proving nothing ever writes the zero frame — the view is born at zero and the grow-delta is missed) is in the linked issue.

Fixes #57520

Changelog:[iOS] [Fixed] - Ensure ScrollView's native scroll view always matches its component view bounds (fixes permanently-invisible ScrollView content when the autoresizing delta is missed)

Test Plan

• On-device verification (iPhone 15 Pro Max, iOS 26.5, RN 0.83.6 + this change applied): under the reproduction conditions (thermal state serious, screen whose ScrollView mounts one frame after the screen, repeated navigation) the desync still occurs and is now corrected within one layout pass — logged heals confirm the code path executes; the invisible-content state no longer reproduces (previously ~every mount).
• Scrolled/RTL/contentOffset behavior unchanged: sizing uses bounds.size + center and preserves bounds.origin (contentOffset) and the RTL transform.
• Existing behavior is unchanged whenever the scroll view already matches its shell (the guard makes the method a no-op).

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