feat: integrate PHPStan, Rector and Pint code quality tools

[Grazulex]

Summary

• Add PHPStan (level max) with Larastan extension for static analysis
• Add Rector with Laravel sets for automated refactoring
• Add Pint with strict rules (final_class, strict_types, etc.)
• Add composer scripts: lint, test:lint, test:types, test:unit, test
• Add GitHub Actions workflow for CI on push/PR to main
• Apply code style fixes across all files
• Update README with Code Quality documentation

Configuration files added

File	Description
phpstan.neon	PHPStan config at max level
rector.php	Rector with 10 Laravel sets + code quality
pint.json	Pint with strict rules
.github/workflows/tests.yml	CI workflow

Scripts available

composer lint        # Apply Rector + Pint fixes
composer test:lint   # Check without fixing
composer test:types  # PHPStan analysis
composer test:unit   # Pest tests
composer test        # Full suite

Test plan

• composer test:lint passes
• composer test:types passes (PHPStan level max, 0 errors)
• composer test:unit passes (11 tests, 39 assertions)
• composer test runs full suite successfully