fix(List): ignore middle mouse button clicks

[BRAUZER06]

Changes:

• Added an onMouseDown handler for ListItem
• When clicking the middle mouse button inside the dropdown list, the event is prevented so that the page autoscroll is not triggered

Why:

• In an open Select, clicking the middle mouse button inside the list area enabled the browser’s autoscroll, which caused the whole page to scroll with the dropdown open
• Many UI libraries disable middle‑click autoscroll inside dropdown lists, so it was decided to remove this behavior here as well

How to test :

1. Open a Select with a long list
2. Click the middle mouse button inside the list area
3. Verify that the page no longer starts autoscrolling and the dropdown remains open

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