Point of Sale preset settings are easier to manage, with clearer labels, direct access from settings, and more flexible default preset selection. The update also prevents deletion of master or actively used presets, reducing the risk of accidental disruption in POS operations.

After this commit:
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- Allowed all presets to be set as default.  
- Added a shortcut to edit presets from settings.  
- Renamed `Others` to `Available` for clarity. 
- Users can select a `default` preset only from `available presets`. 
- Enabled users to change preset identification, even if set as default.  
- Improved field names for better usability.  
- Restricted deletion of master and in-use presets.  

Task: 4523232
Related PR: odoo/odoo#202640

The Barcode app now handles scanned packaging units more accurately during inventory and transfer operations. Quantities entered through the keypad respect the product’s unit settings, and scanned packaging can be used directly as the line unit, reducing picking and transfer errors.