fix(bedrock): update inference profile prefixes

[stevehodgkiss]

Description

I was attempting to use req_llm with caching enabled and noticed some unexpected behaviour. It was falling back to the converse API due to the inference profile I was using (au.anthropic.claude-sonnet-4-5-20250929-v1:0). This PR adds au and some other missing inference profile prefixes to the logic that strips/normalizes the model id for amazon bedrock.

Fix identified/fixed by claude code (opus 4.6):

⏺ Here's the chain that caused the fallback:

1. get_model_family("au.anthropic.claude-sonnet-4-5-...") calls strip_region_prefix (line 926)
2. Old strip_region_prefix didn't have "au" in its list, so it returned "au.anthropic.claude-sonnet-4-5-..." unchanged
3. @model_families lookup (line 930) checked if the normalized ID starts with "anthropic." — but it started with "au.", so no match → found_family = nil
4. Fallback prefix extraction (line 937) split on . → got "au" as the family
5. Back in determine_use_converse, get_formatter_module("au") found no entry in @model_families → returned the Converse module as fallback
6. is_fallback_to_converse (line 1152) was true → returned true at line 1177

I went with the current approach of only stripping a list of known inference profile prefixes.

Setting use_converse: false doesn't fix the issue:

To summarize the error: even with use_converse: false, the Hex version of req_llm (without the au prefix fix) still uses the Converse formatter to build the request body because get_model_family("au.anthropic...") returns "au" → no matching formatter → falls back to Converse formatter. So the endpoint is /invoke but the body is Converse-formatted — causing the "type: Field required" error.

Type of Change

• Bug fix (non-breaking change fixing an issue)
• New feature (non-breaking change adding functionality)
• Breaking change (fix or feature causing existing functionality to change)
• Documentation update

Testing

• Tests pass (mix test)
• Quality checks pass (mix quality)

Checklist

• My code follows the project's style guidelines
• I have updated the documentation accordingly
• I have added tests that prove my fix/feature works
• All new and existing tests pass
• My commits follow conventional commit format
• I have NOT edited CHANGELOG.md (it is auto-generated by git_ops)