[Bron Davies (brondavies)]

Summary:

Fixes #3149. When a focused single-line TextInput is resized, NSTextField moves the field editor's clip view to the cell's drawing rect. That drops the title rect's padding and vertical centering, so the text and placeholder jump to the top of the field.

RCTUITextField now relocates the field editor after a resize, as setTextContainerInset: already does after a padding change. Both share one method, which keeps the selection. It runs only when the size actually changes.

Test Plan:

RNTester-macOS (Debug, arm64, Xcode 27.1, macOS 26.6.2). The Playground had a 40pt search field that shows a Cancel label beside it on focus. I focused it, then read the field editor's clip view from lldb:

• On main, the clip view goes to y 0 once Cancel narrows the field, and the placeholder draws at the top.
• With this change, it stays at y 10.5, centered, and the placeholder stays put.

I also narrowed and widened a focused field with "Hello" typed and the caret after "He". The text stayed centered, and the caret stayed at 2.

I didn't test with a real click; focus came from focus(). It's the same in an app on 0.83.0, with padding in place of the centering.

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