[levibuzolic]

Summary:

Fixes #58157.

On iOS 17.2, a single-line TextInput with caretHidden can repeatedly log Surface 1073741823 x 1073741823 is too large as the caret moves. This can also stop XCUITest from considering the app idle.

The problem comes from returning CGRectZero for the caret.

This PR leaves the rectangle alone and hides the caret with a transparent tint instead. Non-empty selections still use selectionColor, so their highlights and handles remain visible.

The tint is also updated after typing replaces a selection, and when switching between single-line and multiline inputs. Otherwise, those transitions can leave the caret visible or lose the selection color.

Changelog:

[IOS] [FIXED] - Prevent hidden TextInput carets from causing repeated Metal surface errors.

Test Plan:

Built RNTester from source and ran RCTUITextFieldTests on an iPhone 16 simulator with iOS 18.0 and Xcode 27.1. All 10 tests passed with Address Sanitizer and Undefined Behavior Sanitizer enabled. The tests are now included in the RNTester unit-test target and run by iOS CI.

Also checked typing, replacing selected text, selection highlights and handles, and switching between single-line and multiline inputs in RNTester. The caret stayed hidden and selections kept their configured color. No matching surface errors appeared in the logs. Formatting checks passed.

The original iOS 17.2 repro produced 615 errors in 15 seconds before the fix and none afterward. I couldn't repeat that check after rebasing because the 17.2 runtime isn't installed here.

The full RNTester test build hit a Swift compatibility linker error in RNTesterIntegrationTests (__swift_FORCE_LOAD_$_swiftCompatibility56), so I ran the unit-test target separately. Mac Catalyst and physical devices weren't retested.

Native test command

xcodebuild test \
  -workspace packages/rn-tester/RNTesterPods.xcworkspace \
  -scheme RNTesterUnitTests \
  -configuration Debug \
  -sdk iphonesimulator \
  -destination 'platform=iOS Simulator,id=9FB84EC1-1702-4AD9-9E82-BAD3F5A2EC0F' \
  -derivedDataPath ../RNTesterBuild \
  -resultBundlePath ../CaretUnitTests5.xcresult \
  -enableAddressSanitizer YES \
  -enableUndefinedBehaviorSanitizer YES \
  -only-testing:RNTesterUnitTests/RCTUITextFieldTests \
  CODE_SIGNING_ALLOWED=NO