Visual datasets

The first release of deepSTRF focuses on auditory datasets and models. A working video API is on the roadmap but not yet shipped on develop; the deepSTRF.datasets.video namespace currently exposes only the VideoNeuralDataset base class so the audio/video module layout mirrors cleanly.

Earlier drafts of video dataset loaders (Allen Ophys, Allen Ecephys, CRCNS PVC1/PVC11, CRCNS MT1/MT2, CRCNS VIM2, MICrONS, UW Neural Data Challenge) have been parked on the archive/video-api-v0 branch and will be revived, rewritten against the modernized base class, and merged back as the video API stabilizes.