Record resolved decisions in the work item activity feed

Richard Chanrequested to merge
630036-log-decision-resolution-in-activity-feed into master

What does this MR do and why?

Record resolved decisions in the work item activity feed

Decisions resolved through the decision log left no trace in the activity feed, so readers had to open the panel to learn one was made. A system note now links the decision text to its card. The note follows the widget's visibility rule so it never shows decisions to users who cannot see the panel.

Related to #630036

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #630036

Merge request reports