Add Japanese translation and support for multiple languages

[kdmsnr]

• Added Japanese translation (cardcontent_ja.py).
• Split language files to support additional languages in the future (e.g., cardcontent_XX.py).
• Added IDs (e.g., event_id) to cardcontent to enable merging of content across different language files, ensuring specific events, stories, and problems are matched by their respective IDs.