* fix(provider): add missing index field to streaming tool_call deltas
- Fix#6661: Streaming tool_call arguments lost when OpenAI-compatible proxy omits index field
- Gemini and some proxies (e.g. Continue) don't include index field in tool_call deltas
- Add default index=0 when missing to prevent ChatCompletionStreamState.handle_chunk() from rejecting chunks
Fixes#6661
* fix(provider): use enumerate for multi-tool-call index assignment
- Use enumerate() to assign correct index based on list position
- Iterate over all choices (not just the first) for completeness
- Addresses review feedback from sourcery-ai and gemini-code-assist
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Co-authored-by: Yaohua-Leo <3067173925@qq.com>
Co-authored-by: Soulter <905617992@qq.com>