Fix normalized Anthropic max token defaults

[fallintoplace]

Summary

• recognize normalized Anthropic model IDs when applying default max_tokens
• cover the regression through the createStripe() and createStripeV3() provider paths
• keep the fix narrowly scoped to the existing V2 and V3 matchers

Testing

• npm test -- --runTestsByPath provider/tests/stripe-provider.test.ts provider/tests/stripe-provider-v3.test.ts provider/tests/stripe-language-model.test.ts provider/tests/stripe-language-model-v3.test.ts
• ./node_modules/.bin/tsc -p . --noEmit

Closes #432.

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