Garbled output when using Japanese characters

[hl-jm]

Describe the bug
When using -c, every other column will be black boxes.
When using -bc, every other column will have latin letters in black boxes.

To Reproduce
Steps to reproduce the behavior:

1. clone repo, make sure it's at latest commit
2. cmake -G Ninja -B build . && cmake --build build
3. ./build/cmatrix -c

Expected behavior
Katakana characters to be displayed in every column.

Screenshots

cmatrix -c

cmatrix -bc

• OS: Ubuntu via WSL (Win11 v24H2)
• Version 24.04

Additional context
GCC: Ubuntu 13.3.0-6ubuntu2~24.04
ld: 2.42
CMake: 3.28.3
Ninja: 1.11.1
Ncurses: 6.4+20240113-1ubuntu2
bash: 5.2.21(1)-release