fix: fail closed on unusable Codex auth during sandbox auth merge

When reusing a Codex sandbox, the workspace-restore step now performs
an auth-merge check before adopting the sandbox's auth.json. The merge
fails closed when:

- host or sandbox Codex auth is unusable (missing token or account)
- the subscription payload shapes differ between host and sandbox
- subscription account identities do not match

Additional hardening: node absence on PATH during the embedded decision
script now exits non-zero instead of silently falling through. Co-change
comments link parseAuth (the embedded script) to hasUsableAuthPayload
(codex-home.ts) so a future auth-format change cannot silently diverge
between the two implementations.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

.github/workflows/e2e.yml

@@ -0,0 +1,46 @@
+name: E2E Tests
+
+on:
+  workflow_dispatch:
+    inputs:
+      skip_llm:
+        description: "Skip LLM-dependent assertions (default: true)"
+        type: boolean
+        default: true
+
+jobs:
+  e2e:
+    runs-on: ubuntu-latest
+    timeout-minutes: 30
+    env:
+      PAPERCLIP_E2E_SKIP_LLM: ${{ inputs.skip_llm && 'true' || 'false' }}
+      ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
+    steps:
+      - uses: actions/checkout@v7
+
+      - uses: pnpm/action-setup@v6
+        with:
+          version: 9
+
+      - uses: actions/setup-node@v6
+        with:
+          node-version: 20
+          cache: pnpm
+
+      - run: pnpm install --frozen-lockfile
+      - run: pnpm build
+      - run: google-chrome --version
+
+      - name: Run e2e tests
+        env:
+          PAPERCLIP_PLAYWRIGHT_CHANNEL: "chrome"
+        run: pnpm run test:e2e
+
+      - uses: actions/upload-artifact@v7
+        if: always()
+        with:
+          name: playwright-report
+          path: |
+            tests/e2e/playwright-report/
+            tests/e2e/test-results/
+          retention-days: 14