Add default theme management to branding settings and admin interface

src/contexts/BrandingContext.jsx

@@ -1,23 +1,29 @@
 import { createContext, useContext, useState, useEffect, useCallback } from 'react';
 import api from '../services/api';
+import { useTheme } from './ThemeContext';
 
 const BrandingContext = createContext();
 
 export function BrandingProvider({ children }) {
+  const { applyBrandingDefault } = useTheme();
   const [branding, setBranding] = useState({
     appName: 'Redlight',
     hasLogo: false,
     logoUrl: null,
+    defaultTheme: null,
   });
 
   const fetchBranding = useCallback(async () => {
     try {
       const res = await api.get('/branding');
       setBranding(res.data);
+      if (res.data.defaultTheme) {
+        applyBrandingDefault(res.data.defaultTheme);
+      }
     } catch {
       // keep defaults
     }
-  }, []);
+  }, [applyBrandingDefault]);
 
   useEffect(() => {
     fetchBranding();