Wrong FEN for castling

[rmheider]

Describe the bug

When setting up positions manually and then trying to analyze them, the engines often say "Error
illegal position: invalid castling rights". Looking at the FEN, I realized that instead of the letters KkQq, I get "H" and "h".

Reproduction

1. Manually set up a position with the mouse. Make white castle with the mouse.
2. Try to correct the castling rights by clicking the boxes
3. See that "H" or "h" has appeared in the FEN

Platform and versions

Version: 0.11.1
Tauri version: 1.6.1
OS: Linux x86_64 12.0.0

Stack trace