JS improvements
This issue contains a list of improvements for the JS part of BitcartCC-our admin and store:

- [ ] Fine-tune vuetify to reduce loading times and bundle size
- [ ] Ensure images are loaded from onion url if available
- [ ] Optimize loading times, check google page insights guidelines
- [ ] Pin dependencies or create something to avoid regressions because of broken dependencies
- [ ] Reduce the number of dependencies used
- [ ] Set up tests for everything, just like it's done in Python, but more: unit tests, functional tests, e2e tests, UI tests, to easily find out what has got broken (it is required before we make an 1.0 release)
- [ ] General improvements