fix: prevent message duplication in analysis refinement

[xharauenea]

Updated the refineAnalysis function to return only new messages, eliminating duplication caused by the previous implementation that appended all messages to the state. This change ensures cleaner state management in the reducer.

Description

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Type of change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 🔄 Refactor (code change that improves maintainability)
• 📚 Documentation update
• 🔧 Configuration or build change
• ⚡ Performance improvement
• 🚨 Breaking change (fix or feature that would cause existing functionality to change)

Motivation and Context

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How has this been tested?

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Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have run npm run lint and fixed any issues
• I have run npm run prettier to format my code

Breaking Changes

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• Yes (please describe):

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