- Add sort.go with depth-based utilities (GetHierarchyDepth, SortByDepth, GroupByDepth) - Sort issues by hierarchy depth before batch creation - Create in depth-order batches (0→1→2→3) - Fixes latent bug: parent-child pairs in same batch could fail if wrong order - Comprehensive tests for all sorting functions - Closes bd-37dd, bd-3433, bd-8b65 Part of bd-d19a (Fix import failure on missing parent issues) Amp-Thread-ID: https://ampcode.com/threads/T-44a36985-b59c-426f-834c-60a0faa0f9fb Co-authored-by: Amp <amp@ampcode.com>