Choice autocomplete incorrect for enums

[berndbohmeier]

When using enums, the autocomplete doesn't give a value that works, as it doesn't use the same code to normalize.

Use an enum like

import enum

class MyEnum(enum.Enum):
    foo = "bar"

with

@click.choice(MyEnum)

The accepted value for the argument will be "foo", but the autocompleted value is "MyEnum.foo"

Environment:

• Python version: 3.13.4
• Click version: 8.2.1

I think I know how to fix it roughly, so I can open a PR.