Add /models endpoint to list available AI models

[vanshjohri09-collab]

Summary

Add a new API endpoint /models that returns the list of available AI models and the default model configured in the application.

Problem

Currently, clients using the API do not have a way to know which AI models are available or which model is set as default without inspecting the server configuration.

Solution

This pull request introduces a new GET /models endpoint that:

• Returns the list of available AI models
• Returns the default model defined in the settings

This improves API discoverability and makes it easier for clients to dynamically select or display available models.

Changes

• Added /models endpoint in app/routes/api.py
• Endpoint returns available models and default model from configuration

[amannaik247]

There are no 'available' models in sugar ai. Any developer right now can use whatever model they need using the hugging face library by directly updating the .env file variable.

In your code you seem to have created an arbitrary list of model names? I don't understand the reason for that.

[vanshjohri09-collab]

My intention was to make it easier to see which model is currently configured in the API
I understand that Sugar-AI does not keep a fixed list of models and that developers can configure any model through the .env file I can update the endpoint so it only returns the currently configured model instead of a static list
Please let me know if that would be a better approach and I will update the code