update CI4 to 4.6.0 + use codeigniter-vite and vite-plugin-codeigniter to load assets

update php and js packages to latest

update composer dependencies to latest

refs #321

episode page was unaccessible on with php8.1 and dev mode

- update CI4 to v4.1.9's stable production package
- update php and js dependencies to latest

- rename podlibre to adaures
- rename castopod-host to castopod
- simplify README and redirect to docs site
- move INSTALL and UPDATE docs
- add new gitlabci pipeline to deploy docs
- upgrade node to v16 in Dockerfile

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