test: CI smoke test — Docker image builds and starts healthy

[icebear0828]

Goal

GitHub Actions workflow that builds the Docker image and verifies the container starts healthy.

Workflow file

.github/workflows/docker-smoke-test.yml

Trigger

on:
  push:
    branches: [master]
  pull_request:
    branches: [master]

Steps

1. docker build -t codex-proxy-test .
2. Start container: docker run -d -p 8080:8080 --name smoke codex-proxy-test
3. Wait up to 30s for healthy, then curl -f http://localhost:8080/health
4. docker rm -f smoke

Hard constraints — violations = auto-reject

• Branch is master, NOT main
• Package manager is npm — no pnpm/yarn
• Do NOT modify .gitignore, Dockerfile, package.json, package-lock.json, or any existing file
• Do NOT add any new dependencies
• The workflow is pure shell + Docker — no Node.js test runner needed
• Do NOT create test files — this is a workflow-only change (1 new file)
• Runner: ubuntu-latest

Reference

• Dockerfile is at repo root
• Health endpoint: GET /health → 200
• Port configured in config/default.yaml as server.port: 8080