[3/8] Run Python SDK tests in CI (#21895)

## Why

The Python SDK stack now depends on packaging metadata, pinned runtime
wheels, generated artifacts, async behavior, and stream interleaving.
Those checks need to run in CI so future changes cannot bypass the SDK
test suite.

## What

- Add a dedicated `python-sdk` job to `.github/workflows/sdk.yml`.
- Run the job in `python:3.12-alpine` so dependency resolution exercises
the pinned musl runtime wheel.
- Keep the Python SDK test job parallel to the existing SDK job instead
of serializing the full workflow.

## Stack

1. #21891 `[1/8]` Pin Python SDK runtime dependency
2. #21893 `[2/8]` Generate Python SDK types from pinned runtime
3. This PR `[3/8]` Run Python SDK tests in CI
4. #21896 `[4/8]` Define Python SDK public API surface
5. #21905 `[5/8]` Rename Python SDK package to `openai-codex`
6. #21910 `[6/8]` Add high-level Python SDK approval mode
7. #22014 `[7/8]` Add Python SDK app-server integration harness
8. #22021 `[8/8]` Add Python SDK Ruff formatting

## Verification

- The added workflow job installs the SDK with `uv sync --extra dev
--frozen` and runs the Python SDK pytest suite.

---------

Co-authored-by: Codex <noreply@openai.com>

.github/workflows/sdk.yml

@@ -6,6 +6,39 @@ on:
   pull_request: {}
 
 jobs:
+  python-sdk:
+    runs-on:
+      group: codex-runners
+      labels: codex-linux-x64
+    timeout-minutes: 10
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+        with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
+          persist-credentials: false
+
+      - name: Test Python SDK
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          # Run inside Alpine so dependency resolution exercises the pinned
+          # runtime wheel on the same Linux wheel family that CI installs.
+          docker run --rm \
+            --user "$(id -u):$(id -g)" \
+            -e HOME=/tmp/codex-python-sdk-home \
+            -e UV_LINK_MODE=copy \
+            -v "${GITHUB_WORKSPACE}:${GITHUB_WORKSPACE}" \
+            -w "${GITHUB_WORKSPACE}/sdk/python" \
+            python:3.12-alpine \
+            sh -euxc '
+              python -m venv /tmp/uv
+              /tmp/uv/bin/python -m pip install uv==0.11.3
+              /tmp/uv/bin/uv sync --extra dev --frozen
+              /tmp/uv/bin/uv run --extra dev pytest
+            '
+
   sdks:
     runs-on:
       group: codex-runners