test: add e2e test for Qwen3 tool call streaming truncation issue

[devin-ai-integration]

Test for Qwen3 Tool Call Streaming Truncation Issue

This PR adds an end-to-end test that reproduces a streaming truncation issue specifically occurring with Qwen3-235B's tool call responses in OpenRouter.

Issue Details

• When using Qwen3-235B through OpenRouter, tool call arguments get truncated mid-JSON (e.g., {"query": "latest news", "c instead of the complete {"query": "latest news", "count": 5})
• The sequence ends prematurely with a reasoning field containing /tool_call>
• The test verifies that the SDK correctly handles this edge case by coercing invalid JSON to an empty object

Test Implementation

• Creates mock response chunks that simulate the truncation issue
• Verifies the streaming output contains the expected tool call delta with truncated arguments
• Checks that a reasoning part with /tool_call> content is present
• Confirms that the SDK coerces invalid JSON arguments to an empty object {}

Link to Devin run

https://app.devin.ai/sessions/1289ebbccea141e787ae452cc850ad00

Requested by: Louis ([email protected])

[devin-ai-integration]

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