fix(ios): replace crash-causing RCTAssert with RCTLogWarn in touch handler

[hryhoriiK97]

Summary:

On iOS 17+, UITextView's text selection gesture recognizer can deliver touchesMoved:/touchesEnded: to RCTSurfaceTouchHandler without a prior touchesBegan: for the same touch. This happens because UIKit's internal selection gesture claims the touch begin exclusively and only forwards subsequent phases to sibling gesture recognizers.

When this occurs, _activeTouches.find(touch) returns end(), and the RCTAssert fires — throwing an NSException that crashes the app in debug builds. The existing if (iterator == end) { continue; } guard already handles this case gracefully (and is the only code path exercised in release builds, where RCTAssert is a no-op).

This PR downgrades the assertion to RCTLogWarn, preserving the diagnostic signal while eliminating the debug-only crash.

This issue was discovered while investigating text selection crashes in react-native-enriched-markdown, where a custom UITextView-based Fabric component with rich text formatting (headings, paragraphs) consistently triggers the assertion during normal selection gestures.

Changelog:

[IOS] [FIXED] - Fix debug-only crash "Inconsistency between local and UIKit touch registries" in RCTSurfaceTouchHandler triggered by UITextView selection gestures on iOS 17+

Test Plan:

1. Create a React Native app with a multiline <TextInput> or a custom UITextView-based Fabric component
2. On iOS 17+ simulator or device, in a debug build:
   • Tap to place the cursor in a text block
   • Attempt to select text by long-pressing and dragging to a different paragraph
3. Before this fix: App crashes with NSException: "Inconsistency between local and UIKit touch registries"
4. After this fix: Selection works normally. A warning is logged to the console: "Inconsistency between local and UIKit touch registries"
5. Verified that release builds are unaffected (RCTAssert was already a no-op in release)