feat: update fixed weight decoder for improved performance and add tr…

[ArnavBhalla]

…aining data collection

• Changed publish rate from 10 Hz to 30 Hz in fixed_weight_decoder.hpp for better responsiveness.
• Added a new Python script (collect_training_data.py) to collect paired training data from the Synapse app.
• Created easy_test.json and easy_train.json configurations for testing and training modes.
• Implemented a BCI game (bci_game.py) for a 60-second selection task using joystick input.
• Added a run script (run.sh) to facilitate launching the game in demo or device mode.
• Developed a training script (train_decoder.py) to train a PyTorch model for joystick direction decoding and export it to ONNX format.