umbrella issue for all DXF/global-sort/import-into/add-index issues found by AI

# Enhancement
as title, this issue doesn't include any direct issue, just work as a umbrella issue

This is an umbrella issue covering DXF, global sort, import-into, and add-index work, but it names no files, tests, entry points, or direct child issue. Start by finding the underlying issues for those areas; completion criteria are not defined here beyond coordinating the resulting work.

Written by the indexing model from the issue text.