feat(exa-js): add deep-max search type

[maxwbuckley]

Summary

Adds deep-max to the DeepSearchType union, aligning the JS SDK with the API which already accepts this type. This means deep-max now gets proper TypeScript type support and additionalQueries is correctly allowed with it (via DeepSearchOptions).

Review & Testing Checklist for Human

• Verify deep-max is live and accepted by the API (the docs page lists it, and Vulcan's SearchTypeSchema includes it)
• Confirm deep-max should support additionalQueries — by being in DeepSearchType, it inherits DeepSearchOptions which includes that field

Notes

Companion PR for exa-py adds the same type there.

Link to Devin session: https://app.devin.ai/sessions/37d00c74a58c46af92847ccdad46699e
Requested by: @maxwbuckley

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[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no potential bugs to report.

View in Devin Review to see 1 additional finding.

[devin-ai-integration]

Closing — deep-max shouldn't be a public search type. Will be removed from documentation instead.