Add RESPONSIBLE_USE.md, update README; add LICENSE where missing

Author: deathbycaptcha-dev

README.md

@@ -371,3 +371,7 @@ Both CI systems run the full test suite (74 tests, 158 assertions) on every push
 | Integration Tests | [![Integration](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/deathbycaptcha/deathbycaptcha-api-client-php/master/.badges/integration/badge.json)](https://github.com/deathbycaptcha/deathbycaptcha-api-client-php/actions/workflows/tests.yml) |
 | PHP Linting | [![Lint](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/deathbycaptcha/deathbycaptcha-api-client-php/master/.badges/lint/badge.json)](https://github.com/deathbycaptcha/deathbycaptcha-api-client-php/actions/workflows/tests.yml) |
 | PHPStan Analysis | [![PHPStan](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/deathbycaptcha/deathbycaptcha-api-client-php/master/.badges/phpstan/badge.json)](https://github.com/deathbycaptcha/deathbycaptcha-api-client-php/actions/workflows/tests.yml) |
+
+## Responsible Use
+
+See [Responsible Use Agreement](RESPONSIBLE_USE.md).

RESPONSIBLE_USE.md

@@ -0,0 +1,3 @@
+# Responsible Use Agreement
+
+For development and automation against locally hosted or explicitly authorized/demo sites—this library (MIT License) is provided for legitimate use, testing, and research; it must not be used to bypass protections, gain unauthorized access, or target third‑party websites without explicit permission. Users must comply with all applicable laws and third‑party terms, must not publish credentials, and should run examples only against local or consented targets.