feat(edg-fn): support to preview with sentences

[danielebriggi]

No description provided.

[Copilot]

Pull Request Overview

This PR enhances the search edge function to support sentence-based previews instead of simple chunk-based snippets. The implementation retrieves the most relevant sentences within each matching chunk using vector similarity, builds intelligent snippets that maintain document order, and includes gap indicators when sentences are non-contiguous.

Key Changes:

• Introduces sentence-level vector search within matching chunks to identify the most relevant sentences
• Implements smart snippet generation that sorts sentences by document offset and adds gap indicators for non-contiguous selections
• Changes default result limit from 10 to 5 and updates snippet handling to use sentence-based previews

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