Add Boost skill for pest-plugin-ai

[pushpak1300]

Ships a Boost skill at resources/boost/skills/pest-plugin-ai/SKILL.md so AI agents using Laravel Boost get focused, trigger-loaded guidance for the vendor/bin/pest --ai="<code>" workflow — without having to derive it from the broader guideline file.

How to trigger

The skill auto-triggers based on the description in the frontmatter. Phrases that match include:

• "verify this works" / "did my change break X"
• "screenshot the homepage" / "see if the page renders"
• "check this route returns 200" / "make sure the mail fires"
• "test the login form" / "is the form working"
• "check it on mobile"
• Any one-off behavioral check on a Laravel app, or a visual confirmation after a Blade/Livewire/CSS/JS change

The agent then prefers vendor/bin/pest --ai="..." over throwaway test files, tinker, curl, or manual browser checks.

[pushpak1300]

Blocked by #2