Qwen models : system message must be at the beginning

[oukanghua]

Qwen3.5 Qwen3.6 modles system role messages must appear at the beginning of the message list, and there can only be one. When the 'inject JetBrains guidance into OpenCode prompts' option is enabled, it will cause the error.

[webbrain-one]

Thanks for reporting this! I've opened a pull request to address the issue: #9. This fix ensures that system messages for Qwen models are correctly positioned at the very beginning of the message list and prevents duplicates, which resolves the conflict when the "inject JetBrains guidance into OpenCode prompts" option is enabled. Please test it out when you get a chance and let me know if you have any feedback. Thanks again! 🚀