* fix(processMessages): properly handle assistant file citations and add sources list
* feat: improve file download UX by making any downloaded files accessible within the app post-download
* refactor(processOpenAIImageOutput): correctly handle two different outputs for images since OpenAI generates a file in their storage, shares filepath for image rendering
* refactor: create `addFileToCache` helper to use across frontend
* refactor: add ImageFile parts to cache on processing content stream