Agent Skills: Add acceptance test documentation

[bordoni]

Context

Follow-up from PR #242 review feedback by @defunctl. The Agent Skills package currently covers WPUnit integration tests but is missing guidance on acceptance testing.

What to add

Expand the skills/slic/ Agent Skills package with acceptance test documentation covering:

1. Acceptance test suite drivers

• Chromium (WPWebDriver) — use when tests need JavaScript execution, browser interactions, or visual verification. Slower but more capable.
• PHPBrowser — use when tests only need HTML page rendering, form submissions, and redirects (no JavaScript). Significantly faster than Chromium.
• Splitting suites — how to separate JS-dependent acceptance tests from non-JS tests into different suites for faster CI runs (e.g., acceptance-browser and acceptance-phpbrowser).

2. Codeception suite configuration for acceptance

• WPWebDriver module configuration with the slic Chrome service
• WPBrowser (PHPBrowser) module configuration
• How dump.sql is used by the WPDb module in acceptance suites
• Table prefix separation between wpunit and acceptance suites

3. Example test patterns

• Navigating admin screens
• Form submission testing
• JavaScript interaction testing (with Chromium)
• Authentication/login patterns in acceptance tests
• Waiting strategies for async content

Suggested files

• skills/slic/acceptance-tests.md — new file covering the above
• Updates to skills/slic/references/wp-browser-wploader.md to expand the acceptance suite section
• Updates to skills/slic/SKILL.md to link to the new document

Related

• PR Add Agent Skills for AI-assisted WordPress test writing #242 — Add Agent Skills for AI-assisted WordPress test writing