Convert mjlog-XML to tenhou-JSON.
```
mjlog2json 2025010203gm-0000-0000-01234567.xml
mjlog2json 2025010203gm-0000-0000-01234567.xml -o 2025010203gm-0000-0000-01234567.json
mjlog2json input_dir
mjlog2json input_dir -o output_dir
```
```
cargo install mjlog2json
```