fix(exceptions): apply provider-name heuristic to single-positional B…

[vitalii-dynamiq]

…adRequestError

BadRequestError's docstring promises a SUPPORTED_PROVIDERS lookup to disambiguate arcllm's (message, provider, model) from litellm's (message, model, llm_provider). The lookup was only wired into the two-positional branch — a single positional was unconditionally stored as provider.

That broke litellm callers using the most common pattern, BadRequestError("Bad input", "gpt-4o-mini"), which silently landed as provider="gpt-4o-mini" instead of model="gpt-4o-mini". The fix extends the same SUPPORTED_PROVIDERS heuristic to the single-arg branch.

Six new tests pin both shapes (provider-then-model, model-then-provider) across one- and two-positional inputs plus the param-kwarg path. Full unit suite: 798 passed.

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Note

Low Risk
Low risk: narrowly adjusts BadRequestError positional-argument parsing to avoid mislabeling model names as providers, with added unit tests covering the supported positional shapes and param passthrough.

Overview
Fixes BadRequestError positional-argument disambiguation to apply the SUPPORTED_PROVIDERS heuristic to single-positional calls, so BadRequestError(msg, "gpt-4o-mini") is treated as model rather than incorrectly landing in provider.

Adds a focused test suite to pin both arcllm and litellm positional shapes (one- and two-argument forms) and to ensure the param= keyword continues to be preserved.

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