ci(example): add iOS TestFlight publish job alongside Android

Restructures the example app publish workflow as a single workflow with
two parallel jobs (deploy-android, deploy-ios) sharing triggers and
shared composite actions. Both ship together on workflow_dispatch and
on every SDK release.

iOS job mirrors the iOS test app's TestFlight workflow
(klaviyo-ios-test-app/.github/workflows/testflight.yml):

- Ephemeral keychain with Apple Distribution cert
- Per-target Manual signing via xcodeproj Ruby gem (Modern Xcode ignores
  CLI signing flags)
- ExportOptions.plist with provisioning profile UUIDs patched in at
  build time via PlistBuddy
- xcrun altool upload with retry-on-collision (handles manual TestFlight
  uploads racing past github.run_number)
- agvtool sets the build number across all targets per run

RN-specific additions on top:

- Node + Yarn setup before pod install (Metro bundler runs during archive)
- bundle exec pod install --repo-update (no stale CDN pinning)
- Delete .xcode.env.local so Xcode build phase resolves node via $PATH
- GoogleService-Info.plist injected from a base64 secret (versus Android's
  plain-text google-services.json) so Firebase push works in the build

Shared between jobs via composite actions:

- .github/actions/example-publish-prep — verifies KLAVIYO_EXAMPLE_API_KEY
  and writes example/.env
- .github/actions/notify-slack-publish — single notification action with
  result + platform inputs, replacing four duplicated payload blocks

example/ios/ExportOptions.plist is checked in with a GH_actions UUID
placeholder; CI overwrites it with the real UUID per run.

Part of MAGE-464

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

Author: evan-masseau

.github/actions/example-publish-prep/action.yml

@@ -0,0 +1,25 @@
+name: Prepare example app for publish
+description: Verifies the Klaviyo example API key secret is set and writes example/.env so react-native-dotenv can expose it as KLAVIYO_API_KEY at build time.
+inputs:
+  api_key:
+    description: Klaviyo public API key (typically passed from secrets.KLAVIYO_EXAMPLE_API_KEY)
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: Verify Klaviyo example API key is set
+      shell: bash
+      env:
+        KLAVIYO_API_KEY: ${{ inputs.api_key }}
+      run: |
+        if [ -z "${KLAVIYO_API_KEY}" ]; then
+          echo "::error::Klaviyo example API key is empty. The build would produce an app that crashes at launch — set the KLAVIYO_EXAMPLE_API_KEY repo secret."
+          exit 1
+        fi
+
+    - name: Write example/.env
+      shell: bash
+      env:
+        KLAVIYO_API_KEY: ${{ inputs.api_key }}
+      run: echo "KLAVIYO_API_KEY=${KLAVIYO_API_KEY}" > example/.env

.github/actions/notify-slack-publish/action.yml

@@ -0,0 +1,39 @@
+name: Notify Slack of example app publish result
+description: Posts a Slack message summarizing a publish job (success or failure) for the React Native SDK example app.
+inputs:
+  webhook:
+    description: Slack incoming webhook URL
+    required: true
+  result:
+    description: "'success' or 'failure' — drives icon and headline"
+    required: true
+  platform:
+    description: "Human-readable platform label (e.g. 'Play Store', 'TestFlight')"
+    required: true
+  version_label:
+    description: Version string to show in the message (e.g. release tag or 'X.Y.Z (build)')
+    required: false
+    default: manual
+
+runs:
+  using: composite
+  steps:
+    - uses: slackapi/slack-github-action@v2.1.1
+      with:
+        webhook: ${{ inputs.webhook }}
+        webhook-type: incoming-webhook
+        payload: |
+          text: "${{ inputs.result == 'success' && '✅' || '🚨' }} RN SDK Example App: ${{ inputs.platform }} ${{ inputs.result == 'success' && 'publish succeeded' || 'publish failed' }}"
+          blocks:
+            - type: "header"
+              text:
+                type: "plain_text"
+                text: "${{ inputs.result == 'success' && '✅' || '🚨' }} RN SDK Example App: ${{ inputs.platform }} ${{ inputs.result == 'success' && 'publish succeeded' || 'publish failed' }}"
+            - type: "section"
+              text:
+                type: "mrkdwn"
+                text: "*Repository:* ${{ github.repository }}\n*Workflow:* ${{ github.workflow }}\n*Version:* `${{ inputs.version_label }}`\n*Commit:* `${{ github.sha }}`\n*Author:* ${{ github.actor }}"
+            - type: "section"
+              text:
+                type: "mrkdwn"
+                text: "*Workflow Run:* <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|View Details>"