Without this, going to `https://thelounge.example.com/index.html` would return the raw file. This now excludes it from the `public` folder so it cannot be rendered as is.
Renaming the file is for good measure, to indicate that this HTML file must be templated. Because it is a straight rename with no modification, rebasing PRs on it should not be to painful, as git re-applies changes on renamed files.
Also, unread and date markers are now half-transparent based on their colors and not parent opacity. This is necessary to display a non-translucide tooltip.
Also, move the `DedupePlugin` to the prod-specific section. [Webpack doc](https://webpack.github.io/docs/list-of-plugins.html#dedupeplugin) itself recommends to not run this outside of production.
Note that this currently breaks cross-OS support of `npm run build`. This will be fixed in a latter commit.
