* feat(rust): add litellm-s3 crate, AwsCredentialsProvider and cost map fetch
* fix(model-catalog-refresh): time each read instead of the whole cost map download
The 5 s fetch timeout covered the full body, so a slow but steady link failed every attempt where httpx and boto3 would finish. Each read now gets its own 5 s, matching main.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>
