docs: credit Texgriddy and Fredoka; rename the color scheme to Slate

The portal's look is inspired by Texgriddy, an ES-DE theme by
Weestuarty, recreated in CSS without any of its files. The README and
the portal doc now say so, and credit the Fredoka font. The color
scheme was named after Texgriddy's "Chilled" scheme; it's now Slate.

README.md

@@ -192,6 +192,11 @@ and development. Useful starting points:
 - [Ruffle](https://ruffle.rs/), for running Flash in modern browsers.
 - [Selkies](https://github.com/selkies-project/selkies), which streams the
   games.
+- [Texgriddy](https://github.com/Weestuarty/texgriddy-es-de) by Weestuarty, an
+  ES-DE theme that inspired the site's look. The look was recreated from scratch
+  in CSS; none of Texgriddy's files, images or fonts are used.
+- [Fredoka](https://fontsource.org/fonts/fredoka) (SIL Open Font License), the
+  display font.
 
 ## Legal
 

docs/10-features/12-discovery-portal.md

@@ -30,9 +30,15 @@ tokens are applied to `<body>` while the portal is mounted, which takes
 precedence over the app theme on `<html>` and also reaches dialogs and menus
 rendered into the body.
 
-One scheme ships, **Chilled** (slate background, sage boxes). Adding a scheme
+One scheme ships, **Slate** (slate background, sage boxes). Adding a scheme
 means adding an entry to `PORTAL_SCHEMES`; no component changes are needed.
 
+The portal's look is inspired by
+[Texgriddy](https://github.com/Weestuarty/texgriddy-es-de), an ES-DE theme by
+Weestuarty: the framed page, glossy tiles with a metallic ring, outlined info
+boxes, capsule buttons and the slate and sage palette. It was recreated from
+scratch in CSS; none of Texgriddy's files, images or fonts are used.
+
 Display text uses Fredoka (OFL, bundled via `@fontsource-variable/fredoka`);
 body text uses Verdana.
 

frontend/src/components/portal/PortalLayout.tsx

@@ -25,7 +25,7 @@ export function PortalLayout() {
   const searchRef = useRef<HTMLInputElement>(null);
   const [rolling, setRolling] = useState(false);
 
-  useEffect(() => applyPortalScheme('chilled'), []);
+  useEffect(() => applyPortalScheme('slate'), []);
   useMatureSync();
 
   const playRandom = async () => {

frontend/src/components/portal/schemes.ts

@@ -8,8 +8,8 @@ export interface PortalScheme {
 }
 
 export const PORTAL_SCHEMES = {
-  chilled: {
-    label: 'Chilled',
+  slate: {
+    label: 'Slate',
     tokens: {
       '--p-bg': '#4c6878',
       '--p-bg-mix': '#2f4553',