Japanese translation, again.

I've remade the Japanese resources!

```
Improve Japanese translation for natural and modern phrasing

- Use more natural and contemporary Japanese expressions
- Simplify verbose phrases for better readability
- Ensure consistent terminology throughout (e.g., "ユーザーID", "現状維持")
- Replace overly formal expressions with user-friendly language
- Improve clarity of technical descriptions and error messages
- Standardize polite forms (です/ます) consistently
```

I forgot how to send the code 💦
I sent ja/res.rc, a patch for res.rc, and ja/res.po.

I appreciate your help.

-- 
武田洋幸 ヽ(*´ー`*)ノ
TAKEDA Hiroyuki