feat: expose getOctokit factory in script context

Add pre-configured getOctokit factory to the script context, enabling
multi-token workflows directly inside github-script.

- getOctokit(token, opts, ...plugins) inherits action config (retry, userAgent, etc.)
- Deep-merges request and retry options, deduplicates plugins
- stripUndefined prevents baseUrl clobber on GHES
- Integration test job with dynamic repo name (fork-friendly)
- 32 tests passing (15 factory + 4 integration + 6 getOctokit + 7 existing)

.github/workflows/integration.yml

@@ -155,21 +155,51 @@ jobs:
           result-encoding: string
       - run: |
           echo "- Validating user-agent default"
-          expected="actions/github-script octokit-core.js/"
-          if [[ "${{steps.user-agent-default.outputs.result}}" != "$expected"* ]]; then
-            echo $'::error::\u274C' "Expected user-agent to start with '$expected', got ${{steps.user-agent-default.outputs.result}}"
+          ua="${{steps.user-agent-default.outputs.result}}"
+          if [[ "$ua" != "actions/github-script octokit-core.js/"* ]] && [[ "$ua" != "actions/github-script actions_orchestration_id/"* ]]; then
+            echo $'::error::\u274C' "Expected user-agent to start with 'actions/github-script', got $ua"
             exit 1
           fi
           echo "- Validating user-agent set to a value"
-          expected="foobar octokit-core.js/"
-          if [[ "${{steps.user-agent-set.outputs.result}}" != "$expected"* ]]; then
-            echo $'::error::\u274C' "Expected user-agent to start with '$expected', got ${{steps.user-agent-set.outputs.result}}"
+          ua="${{steps.user-agent-set.outputs.result}}"
+          if [[ "$ua" != "foobar octokit-core.js/"* ]] && [[ "$ua" != "foobar actions_orchestration_id/"* ]]; then
+            echo $'::error::\u274C' "Expected user-agent to start with 'foobar', got $ua"
             exit 1
           fi
           echo "- Validating user-agent set to an empty string"
-          expected="actions/github-script octokit-core.js/"
-          if [[ "${{steps.user-agent-empty.outputs.result}}" != "$expected"* ]]; then
-            echo $'::error::\u274C' "Expected user-agent to start with '$expected', got ${{steps.user-agent-empty.outputs.result}}"
+          ua="${{steps.user-agent-empty.outputs.result}}"
+          if [[ "$ua" != "actions/github-script octokit-core.js/"* ]] && [[ "$ua" != "actions/github-script actions_orchestration_id/"* ]]; then
+            echo $'::error::\u274C' "Expected user-agent to start with 'actions/github-script', got $ua"
+            exit 1
+          fi
+          echo $'\u2705 Test passed' | tee -a $GITHUB_STEP_SUMMARY
+
+  test-get-octokit:
+    name: 'Integration test: getOctokit'
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Create secondary client with getOctokit
+        uses: ./
+        id: secondary-client
+        env:
+          APP_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const appOctokit = getOctokit(process.env.APP_TOKEN)
+            const {data} = await appOctokit.rest.repos.get({
+              owner: context.repo.owner,
+              repo: context.repo.repo
+            })
+
+            return `${appOctokit !== github}:${data.full_name}`
+          result-encoding: string
+      - run: |
+          echo "- Validating secondary client output"
+          expected="true:${{ github.repository }}"
+          if [[ "${{steps.secondary-client.outputs.result}}" != "$expected" ]]; then
+            echo $'::error::\u274C' "Expected '$expected', got ${{steps.secondary-client.outputs.result}}"
             exit 1
           fi
           echo $'\u2705 Test passed' | tee -a $GITHUB_STEP_SUMMARY