feat: show database Tracy BarPanel for any Throwable

Added

• docs: describe admin table settings

Changed

• ci(blast.sh): test for presence of phpunit.xml before requiring phpstan/phpstan-phpunit
• feat: use nicer under-construction.html page

Fixed

• fix: add assertions and typecastings to pass PHPStan static analysis at the level: max to make the code more robust
• make sure that the database Tracy BarPanel is displayed when DbmsException is thrown in the model or any other Throwable (TypeError, Error, Exception) is thrown