docs: Update doxygen-awesome-css to 2.4.0 (#2647)

docs/doxygen-awesome-theme/doxygen-custom/toggle-alternative-theme.js

@@ -0,0 +1,52 @@
+// Toggle zwischen drei Theme-Zuständen und speichere im localStorage
+const THEME_CLASSES = ['theme-default', 'theme-round', 'theme-robot'];
+// Ermögliche das Umschalten per Button/Funktion (z.B. für onclick im HTML)
+function toggleThemeVariant() {
+	let idx = getCurrentThemeIndex();
+	idx = (idx + 1) % THEME_CLASSES.length;
+	applyThemeClass(idx);
+}
+
+// Funktion global verfügbar machen
+window.toggleThemeVariant = toggleThemeVariant;
+
+function getCurrentThemeIndex() {
+	const stored = localStorage.getItem('theme-variant');
+	if (stored === null) return 0;
+	const idx = THEME_CLASSES.indexOf(stored);
+	return idx === -1 ? 0 : idx;
+}
+
+function applyThemeClass(idx) {
+	document.documentElement.classList.remove(...THEME_CLASSES);
+	if (THEME_CLASSES[idx] && THEME_CLASSES[idx] !== 'theme-default') {
+		document.documentElement.classList.add(THEME_CLASSES[idx]);
+	}
+	localStorage.setItem('theme-variant', THEME_CLASSES[idx] || 'theme-default');
+	// Select synchronisieren, falls vorhanden
+	const select = document.getElementById('theme-select');
+	if (select) select.value = THEME_CLASSES[idx];
+}
+
+function setThemeByName(themeName) {
+	const idx = THEME_CLASSES.indexOf(themeName);
+	applyThemeClass(idx === -1 ? 0 : idx);
+}
+
+
+document.addEventListener('DOMContentLoaded', () => {
+	const select = document.getElementById('theme-select');
+	if (select) {
+		// Initialisiere Auswahl aus localStorage
+		const idx = getCurrentThemeIndex();
+		select.value = THEME_CLASSES[idx];
+		applyThemeClass(idx);
+		// Theme bei Auswahl ändern
+		select.addEventListener('change', e => {
+			setThemeByName(e.target.value);
+		});
+	} else {
+		// Fallback: Theme trotzdem setzen
+		applyThemeClass(getCurrentThemeIndex());
+	}
+});