Add integration test harness with playwright

[jekkos]

• Add basic Docker integration tests (run-integration-tests.sh)

  • Validates Docker stack startup
  • Checks login page accessibility and HTTP status
  • Verifies login form presence

• Add Playwright E2E test suite

  • Login tests: valid/invalid credentials, protected pages
  • Items tests: create, update, verify in inventory table
  • Customers tests: create with details, search, table verification
  • Sales tests: full sale flow with items, customers, payment, and receipt validation

• Configure Playwright with multi-browser support (Chrome, Firefox)

• Add GitHub Actions workflow for CI/CD

  • Runs on push/PR to master
  • Includes both basic and Playwright tests
  • Uploads screenshots, traces, and logs on failure

• Organize tests in integration-tests/ directory

• Update package.json with test scripts

• Include comprehensive documentation

This provides automated testing for core POS workflows including item management, customer management, and complete sales transactions with receipt generation verification.

[jekkos]

CI Fix Applied

The test failures were caused by docker compose up -d --wait treating the sqlscript init container's successful exit (code 0) as a failure.

Root Cause:

• The sqlscript container is an init container that runs database migrations and exits normally
• docker compose up -d --wait fails when any container exits, even with success code 0
• This prevented the Playwright tests from ever running

Fix:

1. Removed --wait flag from docker compose up command in the workflow
2. The workflow already has a dedicated 'Wait for Application' step that polls the endpoint
3. Removed redundant webServer config from playwright.config.ts since the workflow handles startup separately

The tests should now run properly once the CI re-runs.