feat(backend): added missing untracked files

7project/frontend/src/appearance.ts

@@ -0,0 +1,39 @@
+export type Theme = 'system' | 'light' | 'dark';
+export type FontSize = 'small' | 'medium' | 'large';
+
+const THEME_KEY = 'app_theme';
+const FONT_KEY = 'app_font_size';
+
+export function applyTheme(theme: Theme) {
+  const root = document.documentElement;
+  const body = document.body;
+  const effective = theme === 'system' ? (window.matchMedia && window.matchMedia('(prefers-color-scheme: dark)').matches ? 'dark' : 'light') : theme;
+  body.setAttribute('data-theme', effective);
+}
+
+export function applyFontSize(size: FontSize) {
+  const root = document.documentElement;
+  const map: Record<FontSize, string> = {
+    small: '14px',
+    medium: '16px',
+    large: '18px',
+  };
+  root.style.fontSize = map[size];
+}
+
+export function saveAppearance(theme: Theme, size: FontSize) {
+  localStorage.setItem(THEME_KEY, theme);
+  localStorage.setItem(FONT_KEY, size);
+}
+
+export function loadAppearance(): { theme: Theme; size: FontSize } {
+  const theme = (localStorage.getItem(THEME_KEY) as Theme) || 'light';
+  const size = (localStorage.getItem(FONT_KEY) as FontSize) || 'medium';
+  return { theme, size };
+}
+
+export function applyAppearanceFromStorage() {
+  const { theme, size } = loadAppearance();
+  applyTheme(theme);
+  applyFontSize(size);
+}