Unfork MapBuffer.cpp override added during 0.85 nightly integration

[anuagragith]

Problem Description

During the integration of RN 0.85.0-nightly-20260128-36f07a1b2 (#16245), the upstream MapBuffer.cpp introduced signed/unsigned comparison warnings (C4018 and C4267) that our Warnings.props treats as errors (SDL-mandatory).

• Line 27: header->bufferSize (uint32_t) compared with bytes_.size() (size_t) — C4267
• Line 128: mapBufferLength (int32_t) compared with maxLength (size_t) — C4018

Current Fix:
A local patched copy was created at vnext/ReactCommon/TEMP_UntilReactCommonUpdate/react/renderer/mapbuffer/MapBuffer.cpp with static_cast fixes.

Link to the integration PR where the error originated

#16245

Link to react-native commit

react/react-native@f15985f...36f07a1

Forked files

No response

Upstream PR in react-native

No response

Build Configuration

None