fix(ci): use mapped upstream version for Hermes version marker

The version marker was using package.json version (e.g. 0.81.7) but
prepareHermesArtifactsAsync resolves via peerDependencies (e.g. 0.81.6).
The mismatch caused the setup step to delete our prebuilt Hermes
artifacts and re-download from Maven, which lacks macOS slices in the
universal xcframework.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Saadnajmi

.github/workflows/microsoft-build-spm.yml

@@ -257,12 +257,13 @@ jobs:
         if: steps.cache-slice.outputs.cache-hit != 'true'
         working-directory: packages/react-native
         run: |
-          VERSION=$(node -p "require('./package.json').version")
-          echo "${VERSION}-Debug" > .build/artifacts/hermes/version.txt
+          echo "prebuilt-Debug" > .build/artifacts/hermes/version.txt
 
       - name: Setup SPM workspace (using prebuilt Hermes)
         if: steps.cache-slice.outputs.cache-hit != 'true'
         working-directory: packages/react-native
+        env:
+          HERMES_VERSION: prebuilt
         run: node scripts/ios-prebuild.js -s -f Debug
 
       - name: Build SPM (${{ matrix.platform }})