refactor(store): Extract utility functions into store/utils/

Move pure utility functions from app-store.ts and type files into
dedicated utils modules for better separation of concerns:

- theme-utils.ts: Theme and font storage utilities
- shortcut-utils.ts: Keyboard shortcut parsing/formatting
- usage-utils.ts: Usage limit checking

All utilities are re-exported from store/utils/index.ts and
app-store.ts maintains backward compatibility for existing imports.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/ui/src/store/utils/theme-utils.ts

@@ -0,0 +1,117 @@
+import { getItem, setItem, removeItem } from '@/lib/storage';
+import { DEFAULT_FONT_VALUE } from '@/config/ui-font-options';
+import type { Project } from '@/lib/electron';
+import type { ThemeMode } from '../types/ui-types';
+
+// LocalStorage keys for persistence (fallback when server settings aren't available)
+export const THEME_STORAGE_KEY = 'automaker:theme';
+const FONT_SANS_STORAGE_KEY = 'automaker:font-sans';
+const FONT_MONO_STORAGE_KEY = 'automaker:font-mono';
+
+/**
+ * Get the theme from localStorage as a fallback
+ * Used before server settings are loaded (e.g., on login/setup pages)
+ */
+export function getStoredTheme(): ThemeMode | null {
+  const stored = getItem(THEME_STORAGE_KEY);
+  if (stored) return stored as ThemeMode;
+
+  // Backwards compatibility: older versions stored theme inside the Zustand persist blob.
+  // We intentionally keep reading it as a fallback so users don't get a "default theme flash"
+  // on login/logged-out pages if THEME_STORAGE_KEY hasn't been written yet.
+  try {
+    const legacy = getItem('automaker-storage');
+    if (!legacy) return null;
+    interface LegacyStorageFormat {
+      state?: { theme?: string };
+      theme?: string;
+    }
+    const parsed = JSON.parse(legacy) as LegacyStorageFormat;
+    const theme = parsed.state?.theme ?? parsed.theme;
+    if (typeof theme === 'string' && theme.length > 0) {
+      return theme as ThemeMode;
+    }
+  } catch {
+    // Ignore legacy parse errors
+  }
+
+  return null;
+}
+
+/**
+ * Helper to get effective font value with validation
+ * Returns the font to use (project override -> global -> null for default)
+ * @param projectFont - The project-specific font override
+ * @param globalFont - The global font setting
+ * @param fontOptions - The list of valid font options for validation
+ */
+export function getEffectiveFont(
+  projectFont: string | undefined,
+  globalFont: string | null,
+  fontOptions: readonly { value: string; label: string }[]
+): string | null {
+  const isValidFont = (font: string | null | undefined): boolean => {
+    if (!font || font === DEFAULT_FONT_VALUE) return true;
+    return fontOptions.some((opt) => opt.value === font);
+  };
+
+  if (projectFont) {
+    if (isValidFont(projectFont)) {
+      return projectFont === DEFAULT_FONT_VALUE ? null : projectFont;
+    }
+    // Invalid project font -> fall through to check global font
+  }
+  if (!isValidFont(globalFont)) return null; // Fallback to default if font not in list
+  return globalFont === DEFAULT_FONT_VALUE ? null : globalFont;
+}
+
+/**
+ * Save theme to localStorage for immediate persistence
+ * This is used as a fallback when server settings can't be loaded
+ */
+export function saveThemeToStorage(theme: ThemeMode): void {
+  setItem(THEME_STORAGE_KEY, theme);
+}
+
+/**
+ * Get fonts from localStorage as a fallback
+ * Used before server settings are loaded (e.g., on login/setup pages)
+ */
+export function getStoredFontSans(): string | null {
+  return getItem(FONT_SANS_STORAGE_KEY);
+}
+
+export function getStoredFontMono(): string | null {
+  return getItem(FONT_MONO_STORAGE_KEY);
+}
+
+/**
+ * Save fonts to localStorage for immediate persistence
+ * This is used as a fallback when server settings can't be loaded
+ */
+export function saveFontSansToStorage(fontFamily: string | null): void {
+  if (fontFamily) {
+    setItem(FONT_SANS_STORAGE_KEY, fontFamily);
+  } else {
+    // Remove from storage if null (using default)
+    removeItem(FONT_SANS_STORAGE_KEY);
+  }
+}
+
+export function saveFontMonoToStorage(fontFamily: string | null): void {
+  if (fontFamily) {
+    setItem(FONT_MONO_STORAGE_KEY, fontFamily);
+  } else {
+    // Remove from storage if null (using default)
+    removeItem(FONT_MONO_STORAGE_KEY);
+  }
+}
+
+export function persistEffectiveThemeForProject(
+  project: Project | null,
+  fallbackTheme: ThemeMode
+): void {
+  const projectTheme = project?.theme as ThemeMode | undefined;
+  const themeToStore = projectTheme ?? fallbackTheme;
+  saveThemeToStorage(themeToStore);
+}