## Summary
- Stop sending `anthropic-beta: context-1m-2025-08-07` on Anthropic API
requests.
- `getAiHeaders` remains for future provider-specific headers but
currently returns `undefined`.

## Test plan
- `npm run fmt && npm run lint:fix && npm run ts`
- `npm test` (952 tests)

#skip-bugbot

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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Co-authored-by: Claude <noreply@anthropic.com>