Issue #3627123: Support PHP 8.2 in base policy and approval services

PHP 8.2 cannot parse typed class constants in the base policy and approval services. Remove constant types while preserving names, values and visibility, and declare PHP >=8.2.

Canonical issue: https://www.drupal.org/project/mcp_sentinel/issues/3627123

Adds PHP 8.2 CI coverage for policy, access and approval behavior. Local Drupal 10.6/PHP 8.2 qualification passed 79 tests with 1,100 assertions. Full-repository PHPCS passed on 308 files. Independent review found no outstanding findings.

No merge or release is requested by this submission.