perf: 50x performance improvement for external embeddings (#19296)

* Update utils.py (#77)

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

* refactor: address code review feedback for embedding performance improvements (#92)

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

* fix: prevent sentence transformers from blocking async event loop (#95)

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

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

Author: Classic298