Preserve manually overridden shipping type on quote when quantities change

Description:

When a shipping type is manually set on a quote (overriding the category default), this override is reset to the category default whenever a change is made to the quote, such as a quantity adjustment by the customer or by a salesperson after a retract.

We want an option to lock or preserve the manually selected shipping type, so it survives any subsequent changes to the quote.

Use case:

IT company sets a default shipping type on their categories. In specific cases they want to override this per quote. Currently any edit to the quote resets the shipping type, requiring them to manually re-set it each time.

Expected behavior:

An option to ensure that when I manually set shipping type on quote level it will be preserved when quantities or other fields are updated, unless explicitly changed again. (maybe a toggle when retracting a quote).