Add the Next.js web app and shared lesson content.

Move lessons out of the C sources into JSON so the web client can use the same material as the desktop app, and point release builds at desktop/.

Co-authored-by: Cursor <cursoragent@cursor.com>

tools/extract/themes.mjs

@@ -0,0 +1,48 @@
+import { readFileSync } from 'node:fs';
+import { parseStruct } from '../lib/cparse.mjs';
+
+/** Field order of `ThemePalette` in maturita.h, as the C initializers are positional. */
+const FIELDS = [
+  'crust', 'base', 'mantle', 'surface0', 'surface1', 'surface2',
+  'overlay', 'text', 'subtext', 'accent', 'accent2', 'accent3',
+  'success', 'success2', 'warning', 'error', 'onAccent',
+  'node', 'lockedBg', 'lockedBorder', 'rail',
+  'finishDark', 'finishLight', 'finishStroke',
+];
+
+/** slug, display name, and the C variable prefix used in theme.c. */
+const THEMES = [
+  ['catppuccin', 'Catppuccin', 'cat'],
+  ['nord', 'Nord', 'nord'],
+  ['dracula', 'Dracula', 'dra'],
+  ['rose-pine', 'Rose Pine', 'rose'],
+  ['ocean', 'Ocean', 'ocean'],
+  ['gruvbox', 'Gruvbox', 'gruv'],
+  ['solarized', 'Solarized', 'sol'],
+  ['everforest', 'Everforest', 'ever'],
+  ['monokai', 'Monokai', 'mono'],
+  ['one-dark', 'One Dark', 'one'],
+];
+
+function toPalette(values, label) {
+  if (values.length !== FIELDS.length) {
+    throw new Error(`${label}: expected ${FIELDS.length} colors, got ${values.length}`);
+  }
+  const out = {};
+  values.forEach((v, i) => {
+    if (typeof v !== 'number') throw new Error(`${label}: field ${FIELDS[i]} is not a hex literal`);
+    out[FIELDS[i]] = '#' + v.toString(16).padStart(6, '0');
+  });
+  return out;
+}
+
+export function extractThemes(desktopDir) {
+  const src = readFileSync(`${desktopDir}/theme.c`, 'utf8');
+
+  return THEMES.map(([id, name, prefix]) => ({
+    id,
+    name,
+    dark: toPalette(parseStruct(src, `${prefix}_dark`), `${id} dark`),
+    light: toPalette(parseStruct(src, `${prefix}_light`), `${id} light`),
+  }));
+}