7db7dc9e72
Add Sdt::validate_checksum() method that sums all bytes in the table and verifies the result is zero per ACPI spec. Call it during ACPI table iteration in init() — warn on invalid checksum but do not skip the table, to avoid breaking boot on firmware with slightly incorrect checksums. Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>