Improved Corne (crkbd) Slim Case

Custom remix of another thin case model for the Corne Keyboard with the following adjustments:

- Adjusted the height at which the plate rests so that the plate is aligned with the case.
- The screws fit inside the case so that they do not rest directly on the desk surface and are hidden.
- Improved space where the TRRS connector is housed to allow easy connection of cables with wider ends without hitting the case or being pressed.