Add Symfony 7/8 compatibility

[Kalipso0505]

Summary

• Bump minimum PHP version to >=8.2 (required by Symfony 7+)
• Add Symfony 8 support for symfony/console and symfony/process
• Drop EOL Symfony versions (^3, ^4, ^5)
• Replace deprecated static $defaultName with #[AsCommand] attribute (removed in Symfony 7)
• Replace Application::add() with Application::addCommand() (removed in Symfony 8)
• Remove redundant SUCCESS constant (inherited from Command since Symfony 5.4)
• Replace abandoned qossmic/deptrac-shim with qossmic/deptrac ^2.0
• Clean up all dependency constraints to drop versions incompatible with PHP 8.2+
• Update Dockerfile and CI matrix to match new PHP minimum (8.2, 8.3)
• Replace deprecated ::set-output with $GITHUB_OUTPUT in CI workflows
• Remove delisted symplify/easy-coding-standard-prefixed from suggest
• Simplify PHP_OS_FAMILY check (always defined since PHP 7.2)

Note: PHP 8.4 is not included in the CI matrix because vimeo/psalm ^5.0 does not support PHP 8.4 (highest supported version is ~8.3.0). Once Psalm 6 reaches a stable release with PHP 8.4 support, the CI matrix and the psalm constraint can be updated accordingly.

Test plan

• composer install resolves successfully with Symfony 7.x
• composer install resolves successfully with Symfony 8.x
• bin/phpcstd runs without errors
• CI pipeline passes on PHP 8.2 and 8.3

🤖 Generated with Claude Code