## Problem
We have multiple `Collapsible` components.
## Solution
Reduce their number by using only the one from shadcn.
I haven't noticed any visual nor functional changes.
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## Summary by CodeRabbit
* **Refactor**
* Migrated expandable/collapsible UI to a unified shadcn-based
implementation for more consistent expand/collapse behavior across the
app.
* **Style**
* Updated listbox check icon sizing and removed obsolete collapsible
open/close animations.
* **Chores**
* Removed deprecated collapsible variants and consolidated UI component
surface for simpler maintenance.
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