Panel: Add a "+" button inside layout columns to append blocks (consistent with blocks field UX) #7959
Description
Description:
In Kirby v5.x, adding blocks inside a layout column works differently than adding blocks in a standalone blocks field — which feels like a UI inconsistency.
Current behavior:
If the layout is not empty, the only way to add (custom) blocks inside a layout column is to select an existing block and use its interface. There is no visible "+" button at the bottom of a column to append new blocks. (A "+" button exists below the entire layout field to add new layouts of course, but not inside individual columns.)
Expected behavior:
Each layout column should offer the same "+" button at its bottom as a regular blocks field does, allowing users to append new blocks directly.
Why this matters:
As someone who doesn't use layouts frequently, I was unable to find how to add blocks to a layout column at first. It wasn't immediately clear whether stacking (custom) blocks inside layouts was even possible.
I understand this may be intentional to keep the layout view as close as possible to the rendered page. Still, the inconsistency with the blocks field UX is confusing and worth reconsidering imo.
