fix: improve Bedrock Claude 4.5 model detection for custom ARNs

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Description

This PR fixes an issue where AWS Bedrock was not correctly inferring model capabilities for Claude 4.5 Sonnet when using custom ARNs with cross-region inference.

Problem

When users specified a custom ARN like au.anthropic.claude-sonnet-4-5-20250929-v1:0 with region ap-southeast-2, the model capabilities were incorrectly detected:

• ❌ Context Window: 128,000 tokens (should be 200,000)
• ❌ Max output: 5,000 tokens (should be 8,192)
• ❌ Does not support computer use (should support)
• ❌ Does not support prompt caching (should support)

Solution

1. Enhanced model detection patterns: Reorganized the guessModelInfoFromId method to check more specific patterns first (e.g., claude-sonnet-4-5 before generic claude-4)
2. Added regional prefix support: Extended parseBaseModelId to handle additional regional prefixes including au., af., me., il., cn., and jp.
3. Correct capability assignment: Ensured Claude 4.5 models get the correct capabilities including computer use, prompt caching, and reasoning support

Changes

• Updated guessModelInfoFromId method with more specific pattern matching
• Added support for additional regional inference prefixes in parseBaseModelId
• Ensured proper capability detection for Claude 3.5 and 4.5 models

Testing

• ✅ All existing tests pass
• ✅ Tested with bedrock.spec.ts and bedrock-custom-arn.spec.ts
• ✅ Linting and type checking pass

Fixes #8561

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Important

Fixes AWS Bedrock model detection for Claude 4.5 Sonnet with custom ARNs by updating detection logic and handling regional prefixes.

• Behavior:
  • Fixes incorrect model capability detection for Claude 4.5 Sonnet with custom ARNs in guessModelInfoFromId().
  • Corrects context window, max output tokens, and support for computer use and prompt caching.
• Functions:
  • Updates guessModelInfoFromId() in bedrock.ts to prioritize specific patterns like claude-sonnet-4-5.
  • Extends parseBaseModelId() to handle regional prefixes like au., af., me., etc.
• Testing:
  • Validated with bedrock.spec.ts and bedrock-custom-arn.spec.ts.

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Self-review initiated: a robot judging its own reflection—what could possibly be unbiased.

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P1: Pattern typo prevents detection of Claude 4 Opus; Anthropic naming uses 'claude-4-opus'. This key won't match real IDs like '...claude-4-opus-...'.

Suggested change

	"claude-opus-4": {
	"claude-4-opus": {

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P2: Unverified regional prefix 'jp.' may not be a documented AWS inference profile prefix; stripping it could inadvertently mangle legitimate model IDs. Recommend relying on AWS_INFERENCE_PROFILE_MAPPING or adding tests/docs reference before introducing new prefixes.