[brunohmagro]

Summary:

Backport the lazy ViewManager initialization fix from #58097 (commit da7c29f) to 0.87-stable. The original fix by @fairysword has already landed on main; this PR only adapts it to the supported release branch.

UIManager.js spreads UIManagerImpl, which eagerly evaluates its enumerable lazy ViewManager getters. On Android in Bridgeless mode, importing the module can therefore synchronously call getConstantsForViewManager for registered lazy ViewManagers before their configurations are needed. Copying property descriptors preserves lazy initialization and the existing measurement/command overrides.

The upstream commit does not apply cleanly to 0.87-stable: its callback-typing hunks expect untyped errorCallback parameters, whereas 0.87 already annotates them with (error: Object) => void. This backport retains those existing annotations and omits the now-unnecessary UnsafeObject import. The descriptor-composition fix and regression test are copied from upstream, without additional behavior changes.

This is submitted against the stable branch because of that cherry-pick conflict, as permitted by the release pick process. The fix is absent from 0.87-stable at 2a41d8c. No dependency changes or public API changes are included.

Release pick request: reactwg/react-native-releases#1503

Changelog:

[ANDROID] [FIXED] - Avoid unnecessary getConstantsForViewManager calls during UIManager initialization.

Test Plan:

Executed locally on the 0.87 stable checkout using Node 22.14.0 and Yarn 1.22.22:

• yarn install --frozen-lockfile --non-interactive
• Before the fix: adding the original upstream regression test and running yarn test packages/react-native/Libraries/ReactNative/__tests__/UIManager-test.js --runInBand fails as expected: getConstantsForViewManager is called once during import, where zero calls are expected.
• After the fix: yarn test packages/react-native/Libraries/ReactNative --runInBand passes (2 suites, 4 tests). The test verifies no eager call, an own/enumerable property, and one configuration call across repeated accesses.
• yarn test --maxWorkers=4 passes: 219 suites, 5,662 tests, 1,658 snapshots; 1 test skipped. Jest also reports a worker teardown warning after the passing suites and exits with code 0.
• yarn flow-check --max-workers 4 passes with 0 errors.
• yarn lint --quiet passes.
• yarn format-check passes.
• yarn build-types --validate passes; the public API snapshot is unchanged.
• git diff --check passes.

No fresh Android/iOS native build or device performance benchmark was run for this backport. This PR makes no quantified startup-time claim; native/device validation reported in the original PR remains attributed to that PR's contributors.

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