feat: Add Laravel 13 support

Ensure this package is compatible with Laravel 13. ## Acceptance Criteria - [x] `composer.json` version constraint updated to include Laravel 13.x (e.g. `^10.0|^11.0|^12.0|^13.0`) - [x] CI matrix includes a Laravel 13 job and all tests pass with zero failures on Laravel 13 - [x] Any Laravel 13 breaking changes affecting this package are identified and resolved - [x] README version support table updated to include Laravel 13 - [x] `composer update` completes without conflicts under Laravel 13 ## WSJF | Factor | Score | |--------|-------| | User Value | 7/10 | | Time Criticality | 6/10 | | Risk Reduction | 4/10 | | **Total Numerator** | **17** | | Job Size | 2 | | **WSJF Score** | **8.50** | ## Acceptance Criteria - [ ] laravel-caffeine installs and runs without errors on Laravel 13 - [ ] All existing tests pass on Laravel 13 in CI - [ ] composer.json requires constraint is updated to include Laravel 13 - [ ] CHANGELOG documents Laravel 13 support