refactor(kanban): standardize column width and remove masonry layout

- Remove double-width styling from In Progress column
- Replace masonry 2-column layout with simple vertical stacking
- All Kanban columns now use uniform w-72 width
- Fix Settings view theme consistency with proper CSS variables
- Add action button color variables to theme system

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4 <noreply@anthropic.com>

app/src/components/views/board-view.tsx

@@ -1223,7 +1223,6 @@ export function BoardView() {
                     title={column.title}
                     color={column.color}
                     count={columnFeatures.length}
-                    isDoubleWidth={column.id === "in_progress"}
                     headerAction={
                       column.id === "verified" && columnFeatures.length > 0 ? (
                         <Button