Expose build entry point for AssetRegistry

Summary:
**Problem**

Following D108750303, we now expose an `AssetsRegistry` API from `'react-native'`.

This is great, as we need to replace a deep `/Libraries/...` import in Metro configs (`transformer.assetRegistryPath`):

https://www.internalfb.com/code/fbsource/[31661d52e803d77356725429f44331135601b634]/xplat/js/react-native-github/packages/metro-config/src/index.flow.js?lines=87

**Unfortunately**, we can't quite reuse the new `AssetRegistry` API from the index module, as we'd break Metro's API contract (generate an inline require) — we need a dedicated wrapper module that can be read without destructuring.

**This diff**

Adds a new `'react-native/asset-registry'` secondary entry point, intended/documented for this Metro config use case — and deprecates `react-native/assets-registry/registry`.

- Solves the above problem (migrated in our own `react-native/metro-config` use).
- Remains consistent with D108750302 (we intend to remove `react-native/assets-registry` at a later date).
- As a bonus, fixes the longstanding naming inconsistency between `react-native/assets-registry` and `'react-native/Libraries/Image/AssetRegistry'` — `AssetRegistry` (singular) is now canonical.

Changelog:
- [General][Breaking] - `react-native/Libraries/Image/AssetRegistry` is removed. Please use the `AssetRegistry` API (apps/library code) and/or the `react-native/asset-registry` entrypoint (Metro/build configs).
- [General][Deprecated] - **assets-registry**: `react-native/assets-registry/registry` is deprecated. Please use the `AssetRegistry` API (apps/library code) and/or the `react-native/asset-registry` entrypoint (Metro/build configs).

Differential Revision: D108750303

Author: huntie

packages/assets-registry/README.md

@@ -8,10 +8,14 @@ Most apps never import this directly — assets are handled through `<Image>`.
 
 ## API
 
-### `@react-native/assets-registry/registry`
-
-> [!Note]
-> Aliases to [`AssetRegistry`](https://reactnative.dev/docs/assetregistry) (since 0.87). Prefer importing directly from the `'react-native'` package in libraries.
+### `@react-native/assets-registry/registry` (DEPRECATED)
+
+> [!Warning]
+> **Deprecated**: Aliases to [`AssetRegistry`](https://reactnative.dev/docs/assetregistry) (since 0.87).
+>
+> Please use:
+> - `import { AssetRegistry } from 'react-native';` (apps/library code)
+> - `'react-native/asset-registry'` (entrypoint for Metro/build configs)
 
 | Export | Signature | Notes |
 |---|---|---|

packages/metro-config/src/index.flow.js

@@ -84,7 +84,7 @@ export function getDefaultConfig(projectRoot: string): ConfigT {
     },
     transformer: {
       allowOptionalDependencies: true,
-      assetRegistryPath: 'react-native/Libraries/Image/AssetRegistry',
+      assetRegistryPath: 'react-native/asset-registry',
       asyncRequireModulePath: require.resolve(
         'metro-runtime/src/modules/asyncRequire',
       ),

packages/react-native/Libraries/Image/AssetRegistry.js

@@ -56,6 +56,10 @@
       "react-native-strict-api": null,
       "default": "./types/*.d.ts"
     },
+    "./asset-registry/*": {
+      "types": null,
+      "default": "./src/asset-registry.js"
+    },
     "./gradle/*": null,
     "./React/*": null,
     "./ReactAndroid/*": null,

packages/react-native/package.json

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+// ----------------------------------------------------------------------------
+// Secondary react-native/assets-registry entry point.
+//
+// This is an untyped secondary entry point intended to be referenced from
+// Metro's `transformer.assetRegistryPath` config option.
+//
+// Apps/libraries should prefer `import {AssetRegistry} from 'react-native'`.
+// ----------------------------------------------------------------------------
+
+import {AssetRegistry} from './private/assets/AssetRegistry';
+
+/* eslint-disable @react-native/monorepo/no-commonjs-exports */
+module.exports = {
+  registerAsset: AssetRegistry.registerAsset,
+  getAssetByID: AssetRegistry.getAssetByID,
+};