feat(ai-kit): update docs for Claude 4.5 models support

[sarayev]

Description of changes:

Added documentation for Claude 4.5 model family (Haiku, Sonnet, and Opus) to the supported models table. Included an informational callout explaining that these models use AWS Bedrock global inference profiles for improved availability and cross-region routing.

Related GitHub issue #, if available:

Closes #645

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