fix(ci): set RCT_NEW_ARCH_ENABLED=1 for iOS pod install and archive

Without this env var the Podfile's new-architecture branch doesn't run,
so codegen artifacts like RCTAppDependencyProvider.h are never produced,
even though Pod targets that depend on them (e.g.
ReactAppDependencyProvider) still get wired into the Pods project. The
mismatch surfaces at archive time as
  lstat(.../build/generated/ios/RCTAppDependencyProvider.h):
  No such file or directory
Setting RCT_NEW_ARCH_ENABLED=1 at both the pod install and xcodebuild
steps mirrors what the existing iOS compile CI workflow does for its
new-arch matrix slice and matches RN 0.81's default of new-arch on.

Part of MAGE-464

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: evan-masseau

.github/workflows/publish-example.yml

@@ -213,9 +213,18 @@ jobs:
       # generated by pod install and pins NODE_BINARY at the path of node at
       # install time; we delete it so the Xcode build phase falls back to
       # `command -v node`, which resolves to the setup-node binary on $PATH.
+      #
+      # RCT_NEW_ARCH_ENABLED=1 is required for RN's new-architecture codegen
+      # to run during pod install. Without it, Pods like ReactAppDependencyProvider
+      # are still wired into the Pods project but the codegen outputs they
+      # depend on (e.g. RCTAppDependencyProvider.h) never get generated, and
+      # xcodebuild archive fails on missing headers. RN 0.81's default is
+      # new-arch on; matching that here keeps the example app representative.
       - name: Install CocoaPods dependencies
         working-directory: example/ios
         shell: bash
+        env:
+          RCT_NEW_ARCH_ENABLED: '1'
         run: |
           bundle exec pod install --repo-update
           rm -f .xcode.env.local
@@ -328,6 +337,10 @@ jobs:
           APPLE_TEAM_ID: ${{ secrets.APPLE_TEAM_ID }}
           ASC_KEY_ID: ${{ secrets.APP_STORE_CONNECT_API_KEY_ID }}
           ASC_ISSUER_ID: ${{ secrets.APP_STORE_CONNECT_API_KEY_ISSUER_ID }}
+          # New architecture must be enabled at archive time too — some RN
+          # build-phase scripts read this env var directly to decide whether
+          # to invoke codegen and pull in the generated provider files.
+          RCT_NEW_ARCH_ENABLED: '1'
           # Prevent Metro from trying to start a dev server during the build
           CI: true
         shell: bash