fix: verify branch metadata after snapshot creation (#646)

Description

Checking branch metadata after snapshot creation:

• automated in physical mode
• manual via API request

Related issue

Examples

$ zfs list -t snapshot -o name,dle:parent,dle:child,dle:branch,dle:root,dblab:datastateat -s dblab:datastateat | grep branch
test_dblab_pool/branch/main/clone_pre_20250825153839/r0@snapshot_20250825153840  -                                                                                test_dblab_pool/branch/001-dev@20250825153901,test_dblab_pool/branch/main/clone_pre_20250825154000/r0@snapshot_20250825154000  -           001-dev   20250825153840
test_dblab_pool/branch/001-dev@20250825153901                                    test_dblab_pool/branch/main/clone_pre_20250825153839/r0@snapshot_20250825153840  -                                                                                                                              001-dev     -         20250825153901
test_dblab_pool/branch/main/clone_pre_20250825154000/r0@snapshot_20250825154000  test_dblab_pool/branch/main/clone_pre_20250825153839/r0@snapshot_20250825153840  test_dblab_pool/branch/main/clone_pre_20250825154500/r0@snapshot_20250825154500                                                -           -         20250825154000
test_dblab_pool/branch/main/clone_pre_20250825154500/r0@snapshot_20250825154500  test_dblab_pool/branch/main/clone_pre_20250825154000/r0@snapshot_20250825154000  -                                                                                                                              main        -         20250825154500

Checklist

• MR description has been reviewed
• MR changes are functionally tested
• MR does NOT have API/CLI changes OR there are API/CLI changes and they have been reviewed & DOCS ARE ADJUSTED (reference doc, etc)
• MR does NOT have UI changes OR there are UI changes and they have been reviewed & UX IS REVIEWED

Closes #605 (closed)