Fix docs local preview script

[zerone0x]

Summary

• Update the docs package dev script to use mint dev for Mintlify local preview.
• Leave the existing build script unchanged.

Fixes #12267

Test plan

• node -e "const pkg=require('./docs/package.json'); if (pkg.scripts?.dev !== 'mint dev') { console.error('Expected docs dev script to be mint dev, got:', pkg.scripts?.dev); process.exit(1); } console.log('docs dev script:', pkg.scripts.dev);"
• git diff --check
• Searched the repository for remaining mintlify dev references.

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Summary by cubic

Fix Mintlify local preview by switching the docs package dev script from mintlify dev to mint dev. The build script stays the same.

^{Written for commit 5e5d4fc. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file