fix: return the concat content for array type of function response.

[zhutao100]

The functionResponse should contain the content of the function response, not the generic message for default/unhandled case.

This change fixes commonly used tools like ReadManyFiles, making them correctly return the file contents to LLM.

TLDR

This change fixes commonly used tools like ReadManyFiles, making them correctly return the file contents to LLM.

Reviewer Test Plan

The difference before/after the change can be directly verified by

• open qwen-code in a directory containing some files.
• Write instructions like "read @file1 and @FILE2 to understand them".
• Catch and view the tool request to the server.

Testing Matrix

	🍏	🪟	🐧
npm run	👍	❓	❓
npx	👍	❓	❓
Docker	❓	❓	❓
Podman	❓	-	-
Seatbelt	❓	-	-