feat: add 837 downloads and automated releases

[yannelli]

Summary

• Add single-page and paginated 837 claim downloads with input validation and X12 response handling.
• Support bulk claim archiving through repeated form fields.
• Throw structured exceptions for top-level Claim.MD API errors, including HTTP 200 responses.
• Allow organization enrollments without an NPI or provider first name.
• Correct upload endpoints and multipart boundary handling.
• Add a tested Conventional Commit release workflow that updates the changelog, creates SemVer tags, and publishes GitHub releases.
• Update PHP dependencies and documentation for the expanded SDK behavior and release process.

Why

These changes complete the claim download workflow, improve error visibility and request compatibility, support organization enrollment rules, and make releases consistent and recoverable.

[yannelli]

Courtesy contribution per request - always happy to contribute to open source :)