feat: Initial prototype

appearance.js

@@ -0,0 +1,12 @@
+(() => {
+    let theme = 'system';
+    let language = navigator.language.startsWith('tr') ? 'tr' : 'en';
+    try {
+        const storedTheme = localStorage.getItem('ascii-pwa-theme');
+        const storedLanguage = localStorage.getItem('ascii-pwa-language');
+        if (['system', 'light', 'dark'].includes(storedTheme)) theme = storedTheme;
+        if (['en', 'tr'].includes(storedLanguage)) language = storedLanguage;
+    } catch { /* Preferences remain available without persistent storage. */ }
+    document.documentElement.dataset.theme = theme;
+    document.documentElement.lang = language;
+})();