Update requirements.txt: remove specific version for opencv-python-headless and add numpy

Update TensorFlow version in requirements.txt to latest

Refactor app.py: update app title and description, simplify label handling, and enhance prediction function

Refactor prediction function: enhance image preprocessing, convert to grayscale, and update model input handling

Refactor sketch recognition app: simplify prediction function, update image handling, and remove OpenCV dependency

Refactor sketch recognition app: update app title and description, streamline image processing, and enhance prediction function

Refactor sketch recognition app: enhance image handling, improve error messages, and update app description

Refactor sketch recognition app: update OpenCV dependency to headless version and simplify prediction function

Enhance sketch recognition app: improve image processing in prediction function and add NumPy dependency

Add sketch recognition functionality with TensorFlow and OpenCV