Feature: UI: Implement editing MID in the presence of RELATION_FIELD: MID

[stanislaw]

Description

In 2025-Q4, we have been working on the Linux requirements template proposal. We have introduced the RELATION_FIELD option and the ability to link nodes using MID, not only UID.

Problem

Using MID as a relation field has to be implemented in the UI, so that UI supports MID-based workflow.

Solution

TBD

Additional Information

• Consider reusing the update_node_mid work as per this comment: https://github.com/strictdoc-project/strictdoc/pull/2579/files#r2569966667.