Centralize retained dialog close bindings

docs/modernization/roadmap.md

@@ -496,6 +496,8 @@ callbacks are bound through the overlay service instead of per-panel lambdas.
 Brush, brush-preset, color, layer, grid, stroke, and color-picker popup-panel
 outside-click close handling now shares the same retained release/remove/
 callback helper.
+About, changelog, settings, and user-manual close buttons now share retained
+destroy-on-click binding through the same overlay service.
 Raw popup callback captures and full close/capture ownership remain part of
 `DEBT-0063`.
 `pano_cli inspect-image` exposes PNG IHDR metadata as JSON,