Fix typo in tool use prompt

[mrubens]

Fixes #4207

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Important

Fixes typo in tool use prompt by changing example tool name from read_file to new_task.

• Fixes:
  • Corrects example tool name from read_file to new_task in system.test.ts.snap and tool-use.ts.
  • Affects multiple instances in system.test.ts.snap to ensure consistency in examples.

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