refactor: remove laminas-validator
The legacy validator, its rules and its message map are gone, and with the package go laminas-servicemanager, laminas-stdlib and laminas-escaper. No laminas package is left in the dependency tree.
Not one msgid was lost: the strings the rules need are registered by literal d__() calls in their constructors and factories, so twenty catalogs survive the migration untouched. What the .pot loses is the detailed laminas hostname diagnostics and the CSRF message, none of which the code produces any more.
.agents/validation.md documents the API, the null policy, how to add a rule and where its messages live.