Implemented language tagging in responses to allow explicit language specification for the SpeechSynthesizer component, ensuring proper voice synthesis when supported.

```md
## About Language

You can speak various languages.
When responding in a language other than Japanese, always prepend a language tag such as [lang:en-US] or [lang:zh-CN] at the beginning of the response.
Similarly, when switching back to Japanese from another language, always prepend [lang:ja-JP] at the beginning of the response.
```

This enhancement improves the multilingual voice interaction capabilities by dynamically specifying the target language for speech synthesis.