Paddock 5.0.0

First release of the 5.x line: PHP 8.1+, Symfony 5.4 LTS to 8.0.
The 4.x branch remains available for maintenance.

Compatibility
- PHP ^8.1 (tested from 8.1 to 8.5)
- Symfony ^5.4 | ^6.4 | ^7.4 | ^8.0 (Symfony 4.4 support dropped)

Highlights
- Standalone static binary build (static-php-cli + phpmicro):
  runs on target hosts without any PHP installation
- Installable layout: /etc/paddock/paddock.yaml, conf.d drop-ins and
  layered .env files, inspected with the new paddock:config command
- JUnit report format with file output (-f junit -o <file>) and
  console verbosity filtering
- New Redis component: connection, latency, server info and memory checks
- Proxmox monitoring in Nrpe: VM status, backups and version tracks,
  guided setup with paddock:nrpe:proxmox
- MySQL charset compliance collectors and fixers for tables and columns
- Doctrine ORM 3 / DBAL 4 and DoctrineMongoDBBundle 5 support

Breaking changes
- Gaufrette replaced by Flysystem 3
- Core rule classes renamed to CamelCase (isEqual -> IsEqual, ...);
  rule codes used in YAML tracks are unchanged
- Doctrine mappings moved from annotations to PHP 8 attributes

Quality
- Same test matrix in CI and Docker (make verify)
- PHPStan level 9, PHPMD 3 and PHP-CS-Fixer clean on all components