Sales [XR] XFRM Grid Layout 2.3.6

* Add resource update timeline: star node for Added date + up to 3 most recent update nodes connected by gradient line.
* Show "+N" count badge on first update node when resource has more than 3 updates total.
* Highlight the latest update node with deeper amber and larger size to emphasise recency.

- Upgrade and beautify the interface.

- Fixed bugs from the previous version;
- Improved performance and operational stability.

New option: Resources per page (Admin CP → Options → [XR] XFRM Grid Layout)

Spinbox: Allows selecting from 4 to 120 resources per page (default: 20)

Explain text: Suggests that admins choose a number divisible by the number of columns (such as 12, 16, 20, 24, etc.) so the grid rows remain evenly filled.

Bug fixes and improved stability in certain specific cases.