This implements an _extremely_ basic Firebase-powered gallery (#26). At present it's just a list of links to creatures/manadalas that open in new tabs, without preview thumbnails. Or the ability to submit new entries. These features will be forthcoming in future PRs.
As with #215, this decouples the view logic from Firebase so we can use something else in the future if we want.
This adds GitHub login via Firebase, as a foundation for adding a gallery (#26). Currently it just adds a login/logout button to the Debug page.
At an architectural level, this adds an `AuthContext` React context, whose interface is generic enough that it's not coupled to Firebase or GitHub. In fact, the default context is a "null context" whose operations are all no-ops.
This adds a "random color sampling" section to the right side of the debug page.
I'm hoping this will make it easier for @mittimithai to work on his random color code, since it shows a bunch of random colors (100 right now) side-by-side, rather than requiring the developer to constantly click "randomize colors" on mandala/creature to get an idea of what the color spectrum looks like, 3 colors at a time.
This improves the layout of all our pages to look more like the mandala page.
Additionally, some form widgets now have better layout, and the header takes up less vertical space.
At an implementation level, the component hierarchy of pages has been inverted to make this kind of layout easier. Now fully laid-out pages are contained within `<Page>` components that are at the top of the component hierarchy, and which are defined by each specific page (mandala, creature, vocabulary, etc).
I had to do a few architectural things to avoid circular imports, though; most notably, this involved the creation of a new React context called a `PageContext`.
It uses CSS grid, which should be pretty well-supported amongst recent browsers.
Really the eye creature is only useful for me as a debugging tool, so this moves it over to a separate debug page.
It also removes the whole concept of randomizing the eye creature, mainly because it ignores all the rules set forth in the normal creature randomizer, so it's not terribly useful.
This simplifies the code for `creature-page.tsx` a bunch and hopefully makes it easier to understand.
Atul Varma