Add UI settings API and improve context initialization

- Add /settings/ui GET and PUT endpoints for UI settings
- Improve ThemeContext with better initialization and auto accent handling
- Update SidebarContext with expanded state persistence
- Fix context initialization in ModulesContext and ViewModeContext
- Update components to use improved theme/sidebar contexts

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/src/contexts/ModulesContext.tsx

@@ -1,6 +1,7 @@
 import { createContext, useContext, useState, useEffect, useCallback } from 'react';
 import type { ReactNode } from 'react';
 import { settingsAPI } from '../api/client';
+import { useAuth } from './AuthContext';
 import type { UserPermissions } from '../types';
 
 // User-facing modules that can be toggled
@@ -39,6 +40,7 @@ const getDefaultStates = (): Record<ModuleId, ModuleState> => {
 };
 
 export function ModulesProvider({ children }: { children: ReactNode }) {
+  const { token } = useAuth();
   const [moduleStates, setModuleStates] = useState<Record<ModuleId, ModuleState>>(getDefaultStates);
   const [isLoading, setIsLoading] = useState(true);
   const [hasInitialized, setHasInitialized] = useState(false);
@@ -110,16 +112,18 @@ export function ModulesProvider({ children }: { children: ReactNode }) {
     }
   }, [moduleStates]);
 
-  // Load modules on mount when token exists
+  // Load modules when token becomes available
   useEffect(() => {
-    const token = localStorage.getItem('token');
     if (token) {
+      setIsLoading(true);
+      setHasInitialized(false);
       loadModulesFromBackend();
     } else {
+      setModuleStates(getDefaultStates());
       setIsLoading(false);
       setHasInitialized(true); // No token, mark as initialized
     }
-  }, [loadModulesFromBackend]);
+  }, [token, loadModulesFromBackend]);
 
   const isModuleEnabled = useCallback((moduleId: string): boolean => {
     // Dashboard is always enabled