Negative Commission Rates Accepted

Describe the bug
An issue has been identified in the Multivendor Admin Dashboard where the commission rates for vendors are accepting negative values.

To Reproduce
Steps to reproduce the behavior:

Log in to the Multivendor Admin Dashboard.
Navigate to the section where commission rates for vendors are configured.
Attempt to set a negative value for the commission rate.
Expected behavior
The system should prevent users from entering or saving negative values for commission rates, as negative rates are not valid in this context.

Screenshots
https://github.com/ninjas-code-official/food-delivery-multivendor/assets/152266796/1cbcd911-8f36-43bc-8de1-8498ea3b5a78

Desktop:

Browser: chrome

Start by locating the commission-rate configuration entry point in the backend and reproduce the negative-value case described for the Multivendor Admin Dashboard. Trace where the value is validated or saved, then verify that negative rates are rejected and valid rates continue to work.

Written by the indexing model from the issue text.