fix: default to 4 num_classes

[GabrielLidenor]

📝 Description / Why

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The default num_class was 7 for the model, but our dataset only has 4.

🛠️ PR Changes

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• src/models/emote_vision_model.py - update default num_classes to 4

🧪 Verification & Testing Completed

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📌 Reviewer Checklist

• Code follows the modular structural design of the project.
• Dependencies are cleanly synced and added to requirements.txt if new packages were imported.
• No local datasets, binary files, or credentials are being tracked (Double check .gitignore).
• Pipeline executes end-to-end without throwing runtime exceptions.