feature added: --validate checksum flag (#44)

* feature added: --validate checksum flag

* refactor: address CodeRabbit review comments

* refactor: address CodeRabbit review comments (2)

* refactor: address CodeRabbit review comments (3)

* refactor: address CodeRabbit review comments (4)

* refactor: address review comments (naming, strict checksum extraction)

* refactor: addressed coderabbit suggestions

Author: agrim-git-hub