chore(deps): remove Laravel Nightwatch integration

Drop the laravel/nightwatch package and its agent service from the
development and production s6-overlay configs. Remove the related
environment variables, constants, phpunit setting, Boost skill
registration, and configure-nightwatch agent skills. Update the
container role script test to stop expecting the nightwatch-agent
service.

boost.json

@@ -19,7 +19,6 @@
         "laravel-best-practices",
         "configuring-horizon",
         "mcp-development",
-        "configure-nightwatch",
         "socialite-development",
         "livewire-development",
         "pest-testing",