"Add Areas" sidebar shows duplicate bricks when multiple areablocks exist on a page

[Maxara]

Description
When a document page contains multiple nested areablocks (e.g. main → container → columns), the "Add Areas" sidebar aggregates all allowed bricks across all areablocks, resulting in duplicate entries.

Expected behavior:
Each brick should appear only once in the sidebar, or the sidebar should show bricks grouped by/filtered to the currently selected areablock.
Actual behavior:
Bricks that are allowed in multiple areablock levels appear multiple times. For example:

• snippet allowed in main, container, and columns → shows 3 times
• container allowed in main and columns → shows 2 times
• columns allowed in container and columns → shows 2 times

Configuration example:

areabrick_config:
  main:
	  allowed:
		  - container
		  - snippet          # 1st occurrence                                                                                                                                                                                                   
  container:
	  allowed:
		  - columns
		  - snippet          # 2nd occurrence
  columns:
	  allowed:
		  - accordion
		  - columns
		  - container
		  - snippet          # 3rd occurrence
		  # ... more bricks

Steps to reproduce:

1. Configure multiple nested areablocks with overlapping allowed brick lists
2. Open a document using these areablocks in Studio UI
3. Click "Add Areas" in the sidebar
4. Observe duplicate entries for bricks that appear in multiple areablock allowed lists

Versions:

• pimcore/studio-ui-bundle: 1.x-dev
• pimcore/pimcore: v12.3.2