test(e2e): retry Playground smoke tests in CI to absorb boot flakiness

[dknauss]

Problem

The Playwright Playground smoke job (npm run test:e2e:playground) has been flaking: a single test intermittently times out in the shared ensurePluginActivated helper waiting for the wp-admin Plugins <h1> to render (30s timeout), while 8/9 tests pass — and tests after the timeout also pass, so WordPress is up, just momentarily slow on one request.

This hit main and multiple branches in the same ~16:58 UTC window today (e.g. main run 27969931878), pointing at a transient slowdown of the unpinned @wp-playground/cli@latest server the harness boots — not any code regression. The failing test is non-deterministic (different spec each run), all failing at the identical boot-wait point.

Why it was fatal

playwright.config.js had no retries key, so retries defaulted to 0 in CI. A single transient timeout failed the entire smoke job with no second attempt.

Fix

retries: process.env.CI ? 2 : 0,

Flaky single-test timeouts now self-heal with up to 2 retries in CI; local runs keep fast-fail (retries: 0). The tests run against an ephemeral WordPress instance, so retries are safe and idempotent. Consistent with the repo's existing posture of guarding E2E against editor-not-ready races (d961392).

Verification

• CI= node -e "require('./playwright.config.js').retries" → 0; CI=true … → 2
• npx playwright test --list loads the config and enumerates the suite without error
• Unit tests / lint / build green via pre-commit gate

Note

This is a separate, main-targeted fix because the flake affects main itself, not just #62. Once merged, #62 (and other branches) can be re-run / rebased and will benefit from the retry behavior.

🤖 Generated with Claude Code

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.80%. Comparing base (4918807) to head (1a573ac).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #63   +/-   ##
=======================================
  Coverage   80.80%   80.80%           
=======================================
  Files          44       44           
  Lines        3084     3084           
  Branches      523      523           
=======================================
  Hits         2492     2492           
  Misses        185      185           
  Partials      407      407           

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