fix(web): Keep generated files out of Tailwind's sources in every build
Tailwind skips what .gitignore names only inside a git repository. The
images build the client from a context with no .git, so there it also
read the core bundle copied into public/ (selkies-core.js) and took
words in it for class names: an image's stylesheet carried rules a
checkout's did not, .container with its width and max-width steps,
.blur, .grow, .paused and others (107393 bytes against 105675),
so the client was not the same in every channel.
index.css names the copied core bundle and dist as no source.
The dashboard built in a checkout and in a copy of the image's build
context: the same stylesheet in both, src-e5BndWGk.css, 105675 bytes,
which is the checkout's from before.