fix: ensure version_id is returned in S3 response headers

[loverustfs]

Type of Change

• [ ] New Feature
• [x] Bug Fix
• [ ] Documentation
• [ ] Performance Improvement
• [x] Test/CI
• [ ] Refactor
• [ ] Other:

Related Issues

• #1066

Summary of Changes

• Ensure S3 responses return version_id for PutObject, CopyObject, and CompleteMultipartUpload when versioning is enabled, fixing Veeam VBR compatibility.
• Added a comprehensive regression test suite (version_id_regression_test.rs) covering versioned and non-versioned buckets, multipart uploads, copy flows, and a Veeam-like backup workflow to guard against regressions.

Checklist

• [ ] I have read and followed the CONTRIBUTING.md guidelines
• [ ] Passed make pre-commit
• [x] Added/updated necessary tests
• [ ] Documentation updated (if needed)
• [ ] CI/CD passed (if applicable)

Impact

• [ ] Breaking change (compatibility)
• [ ] Requires doc/config/deployment update
• [x] Other impact: Improves S3 compatibility by returning version IDs; expected to be backward-compatible.

Additional Notes

• Regression tests: cargo test -p e2e_test --lib version_id_regression_test -- --test-threads=1
• Please run full pre-commit (make pre-commit) before merge.