Feature request: Add installed file integrity verification

[chiareu]

CloudPanel already provides SHA256 verification for the installer, which is a good practice.

A similar mechanism for the installed application files could further improve trust and security, especially since some PHP files are obfuscated and may trigger false positives in security scanners.

Possible approaches could be:

• a signed manifest containing file hashes;
• a CLI command to verify CloudPanel core files;
• automatic integrity checks during updates.

This would help administrators confirm that the installed files are genuine and have not been modified, while keeping the current source protection approach.