rename episode activity cache

- configure service-worker using vite-plugin-pwa
- refactor Image entity to generate images of
different types based on size config
- add requirement for webp library for php gd to generate webp
images for instance
- add action to regenerate all instance images for eventual Images config
changes
- enhance google lighthouse metrics for pwa

- refactor meta-tags by generating them in the controller and injecting them into the views
- use
`melbahja/seo` library to build opengraph and twitter meta-tags + schema.org objects