fix: vol-6097 - replace deprecated laminas-crypt with PHP Sodium

[Ahmed7752]

Description

This spike investigates and implements a replacement for the deprecated laminas-crypt package.
After reviewing available options, we migrated to Libsodium for symmetric encryption, using PHP’s built-in sodium extension (PHP supported through 8.2 +).

• Replaced Laminas\Crypt\BlockCipher usage with a new SodiumEncryptor implementing EncryptorInterface
• Added CacheEncryptionFactory and updated cache encryption service to use SodiumEncryptor
• Updated unit tests for:
• SodiumEncryptor
• CacheEncryption
• CacheEncryptionFactory
• Added developer documentation on vol-app repo

Related issue: VOL-6097

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