Fix parallel tool call input bugs

[Ken Jiang (knjiang)]

This PR can be reviewed commit by commit. https://linear.app/braintrustdata/issue/BT-4573/fix-parallel-tools-google-adk-bug-with-anthropic-openai

failures look like:

{
  "error": "400 An assistant message with 'tool_calls' must be followed by tool messages responding to each 'tool_call_id'. The following tool_call_ids did not have response messages: toolu_nyc",
  "name": "Error"
}

First commit:

1. ran make capture which does two things:
   a. snapshots the LLM request/responses for the parallelToolCallsRequest
   b. runs transform_request logic by swapping out models for a different provider to "simulate" LLM transforms.
2. All LLM "passthrough" captures passed and found 2 bugs related to transform logic

  "anthropic_to_chat-completions": {
    "parallelToolCallsRequest": "Bug: parallel tool results in a single Message::Tool are collapsed to one role:tool message; OpenAI rejects with missing tool_call_id"
  },
  "chat-completions_to_google": {
    "parallelToolCallsRequest": "Bug: role:tool messages lack a function name, so functionResponse.name is empty when converting to Google format"
  }

3. document bugs in transform_errors.json which lets CI pass. the CI fails when there are undocumented bugs.

Second commit:

1. remove bugs from transform_errors.json
2. have AI fix the two bugs in transform_errors.json while maintaining lingua best practices
3. once i was happy with the library-level changes in crates/lingua, I ran make regenerate-failed-transforms
   a. make regenerate-failed-transforms only runs the capture script on transforms that have materially changed based on the snapshots in https://github.com/braintrustdata/lingua/blob/main/payloads/scripts/transforms/__snapshots__/transforms.test.ts.snap
4. bugs fixed.

[Ken Jiang (knjiang)]

• Fix parallel tool call input bugs #166 👈 (View in Graphite)
• main

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