Add headers to XCFramework (facebook#52010)

Summary:
We found out that the XCFramework that is generated in CI is missing the headers.
This is happening because we run the setup script, the responsible to prepare the folder structure with the heaeders in the right place, only in the job that builds the slices. However, the headers are copied by the job that composes the XCFramework.

This change stores the header folder as an artifact in the build job and retrieves it in the compose job, so that the files are available to the XCFramework

## Changelog:
[Internal] -

Pull Request resolved: facebook#52010

Test Plan:
Check the generated artefact in CI
<img width="292" alt="Screenshot 2025-06-13 at 15 32 02" src="https://github.com/user-attachments/assets/437333da-5848-4657-a9b3-e87fc79c69b2" />

Reviewed By: cortinico

Differential Revision: D76599834

Pulled By: cipolleschi

fbshipit-source-id: 44d74b5f8df545a825ecfe3df2e1898effe41261

Author: cipolleschi

.github/workflows/prebuild-ios-core.yml

@@ -23,8 +23,8 @@ jobs:
         id: restore-ios-slice
         uses: actions/cache/restore@v4
         with:
-          path: packages/react-native/third-party/
-          key: v2-ios-core-${{ matrix.slice }}-${{ matrix.flavor }}-${{ hashFiles('packages/react-native/Package.swift') }}-${{ hashFiles('packages/react-native/scripts/ios-prebuild/setup.js') }}
+          key: v3-ios-core-${{ matrix.slice }}-${{ matrix.flavor }}-${{ hashFiles('packages/react-native/Package.swift') }}-${{ hashFiles('packages/react-native/scripts/ios-prebuild/setup.js') }}
+          path: packages/react-native/
       - name: Setup node.js
         if: steps.restore-ios-slice.outputs.cache-hit != 'true'
         uses: ./.github/actions/setup-node
@@ -101,6 +101,12 @@ jobs:
           # This is going to be replaced by a CLI script
           cd packages/react-native
           node scripts/ios-prebuild -b -f "${{ matrix.flavor }}" -p "${{ matrix.slice }}"
+      - name: Upload headers
+        uses: actions/upload-artifact@v4
+        with:
+          name: prebuild-ios-core-headers-${{ matrix.flavor }}-${{ matrix.slice }}
+          path:
+            packages/react-native/.build/headers
       - name: Upload artifacts
         uses: actions/[email protected]
         with:
@@ -111,10 +117,10 @@ jobs:
         uses: actions/cache/save@v4
         if: ${{ github.ref == 'refs/heads/main' }} # To avoid that the cache explode
         with:
-          key: v2-ios-core-${{ matrix.slice }}-${{ matrix.flavor }}-${{ hashFiles('packages/react-native/Package.swift') }}-${{ hashFiles('packages/react-native/scripts/ios-prebuild/setup.js') }}
-          enableCrossOsArchive: true
+          key: v3-ios-core-${{ matrix.slice }}-${{ matrix.flavor }}-${{ hashFiles('packages/react-native/Package.swift') }}-${{ hashFiles('packages/react-native/scripts/ios-prebuild/setup.js') }}
           path: |
             packages/react-native/.build/output/spm/${{ matrix.flavor }}/Build/Products
+            packages/react-native/.build/headers
 
   compose-xcframework:
     runs-on: macos-14
@@ -153,6 +159,13 @@ jobs:
           pattern: prebuild-ios-core-slice-${{ matrix.flavor }}-*
           path: packages/react-native/.build/output/spm/${{ matrix.flavor }}/Build/Products
           merge-multiple: true
+      - name: Download headers
+        if: steps.restore-ios-xcframework.outputs.cache-hit != 'true'
+        uses: actions/download-artifact@v4
+        with:
+          pattern: prebuild-ios-core-headers-${{ matrix.flavor }}-*
+          path: packages/react-native/.build/headers
+          merge-multiple: true
       - name: Setup Keychain
         if: ${{ steps.restore-ios-xcframework.outputs.cache-hit != 'true' && env.REACT_ORG_CODE_SIGNING_P12_CERT != '' }}
         uses: apple-actions/import-codesign-certs@v3 # https://github.com/marketplace/actions/import-code-signing-certificates