Address review feedback from bircni and wxiaoguang:
- Add rerender(items, selectedValue) method to IssueSidebarComboList
so any picker can dynamically rebuild its menu. This replaces the
one-off renderColumnPicker function with a framework-level capability.
- Convert the column picker template to use the standard
issue-sidebar-combo structure, so it is initialized by the existing
queryElems loop alongside milestone/label/assignee pickers.
- Move projectColumnInfo struct to package level (bircni)
- Handle ProjectColumnID and MustDefaultColumn errors (bircni)
- Remove custom Fomantic dropdown setup and DOM manipulation
The rerender method is designed to support future multi-project use:
each project's column picker can independently rerender when its
parent project selection changes.