fix: OS Detection of theme removed.

frontend/src/shared-minimal/theme/ThemeContext.tsx

@@ -1,6 +1,6 @@
 /**
  * @ai-summary Theme context for managing light/dark mode across the app
- * Supports: system preference detection, localStorage persistence, backend sync
+ * Supports: localStorage persistence, backend sync, defaults to light theme
  * Applies Tailwind dark class to document root
  */
 
@@ -27,28 +27,6 @@ interface ThemeProviderProps {
   children: ReactNode;
 }
 
-// Detect system dark mode preference
-const getSystemPreference = (): boolean => {
-  if (typeof window !== 'undefined' && window.matchMedia) {
-    return window.matchMedia('(prefers-color-scheme: dark)').matches;
-  }
-  return false;
-};
-
-// Check if user has explicitly set a preference in localStorage
-const hasStoredPreference = (): boolean => {
-  try {
-    const stored = localStorage.getItem(SETTINGS_STORAGE_KEY);
-    if (stored) {
-      const settings = JSON.parse(stored);
-      return settings.darkMode !== undefined && settings.darkMode !== null;
-    }
-  } catch {
-    // Ignore parse errors
-  }
-  return false;
-};
-
 // Read dark mode preference from localStorage
 const getStoredDarkMode = (): boolean | undefined => {
   try {
@@ -65,13 +43,13 @@ const getStoredDarkMode = (): boolean | undefined => {
   return undefined;
 };
 
-// Get initial dark mode: localStorage > system preference
+// Get initial dark mode: localStorage > default to light
 const getInitialDarkMode = (): boolean => {
   const stored = getStoredDarkMode();
   if (stored !== undefined) {
     return stored;
   }
-  return getSystemPreference();
+  return false; // Default to light theme
 };
 
 // Update dark mode in localStorage while preserving other settings
@@ -97,23 +75,6 @@ export const ThemeProvider = ({ children }: ThemeProviderProps) => {
     setIsInitialized(true);
   }, []);
 
-  // Listen for system preference changes (only when no explicit preference set)
-  useEffect(() => {
-    if (typeof window === 'undefined' || !window.matchMedia) return;
-
-    const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
-
-    const handleChange = (e: MediaQueryListEvent) => {
-      // Only react to system changes if user hasn't set explicit preference
-      if (!hasStoredPreference()) {
-        setIsDarkMode(e.matches);
-      }
-    };
-
-    mediaQuery.addEventListener('change', handleChange);
-    return () => mediaQuery.removeEventListener('change', handleChange);
-  }, []);
-
   // Apply dark class to document root for Tailwind
   useEffect(() => {
     const root = document.documentElement;