switch photography app to use Nomic for embeddings instead of OpenAI+MediaPipe

[vkarpov15]

Right now the photography app uses OpenAI for text embeddings and a locally hosted Python library for image embeddings. Switching both to Nomic offers 2 major advantages:

1. No need to set up Python and MediaPipe
2. Image and text embeddings are now compatible: you can search for images by text embedding. Currently, the app searches for images by the image description text.