aider: Modify Gradio interface to accept an image as input, call `predict_bear_type` with the image, and display the prediction.

aider: Created a function `predict_bear_type(img_path)` that opens the image at the given path, converts it to a PILImage, and uses the learner to predict the type of bear in the image.

aider: Load a fastai learner from `export.pkl` in `app.py`.

aider: Added hello world Gradio app in `app.py`.