fix: extract JSON object/array from mixed LLM responses (#138)

[IamYJLee]

All Supported Input Formats

Input Format	Return	Result
```json\n...\n```	Return parsed JSON output	✅
Explanation...\n```json\n...\n```\nMore text	Return parsed JSON output	✅
Explanation...\n{...}\nMore text	Return parsed JSON output	✅
No JSON here	return raw output	❌ (parse failed)

Conclusion

No matter how the LLM responds, if there is a ```json``` block or a {...} structure, it will be correctly extracted.

[sttlr]

Cool! It'd be nice to add tests for this functionality.

[IamYJLee]

Cool! It'd be nice to add tests for this functionality.

@sttlr Thanks for the review! Feedback addressed.