[feature] Nicer login.html page, with cute styling + link to source code (#19)

Fixes #9

- Cute styling, combination of Mastodon and GTS
- Short description of the project
- Error and status messages (temporarily) appear in disabled button with correct ARIA attributes
- Sufficient contrast (WCAG AAA)

Let me know if using `login.scss` both as an index file and for adding custom styling is okay. I figured this might be preferred over creating an extra folder and file.

Reviewed-on: https://codeberg.org/superseriousbusiness/masto-fe-standalone/pulls/19
Co-authored-by: vyxen <vyxen@tutamail.com>
Co-committed-by: vyxen <vyxen@tutamail.com>

app/javascript/flavours/glitch/packs/login.js

@@ -0,0 +1,8 @@
+import 'packs/public-path';
+import { start } from '@rails/ujs';
+import 'flavours/glitch/styles/login.scss';
+
+start();
+
+//  This ensures that webpack compiles our images.
+require.context('../images', true);