fix(auth): sign out - await logout and use full page redirect

- useSidebarNavigation: was not awaiting logout(), so navigate ran before
  store was updated; LoginPage then saw isAuthenticated=true and
  redirected back to dashboard
- Both Sidebar and Header: use window.location.href instead of
  navigate() for logout redirect to ensure clean state (clears any
  stale React/Query cache, forces fresh load)

apps/web/src/components/layout/Header.tsx

@@ -39,7 +39,8 @@ export function Header(_props: HeaderProps) {
   const handleLogout = async () => {
     setIsUserMenuOpen(false);
     await logout();
-    navigate('/login');
+    // Full page redirect ensures clean state after logout
+    window.location.href = '/login';
   };
 
   const toggleTheme = () => {

apps/web/src/hooks/useSidebarNavigation.ts

@@ -1,5 +1,4 @@
 import { useCallback } from 'react';
-import { useNavigate } from 'react-router-dom';
 import { useAuthStore } from '@/features/auth/store/authStore';
 import { useUIStore } from '@/stores/ui';
 
@@ -12,7 +11,6 @@ const SIDEBAR_BREAKPOINT = 1024;
  * - Déconnexion
  */
 export function useSidebarNavigation() {
-  const navigate = useNavigate();
   const { logout } = useAuthStore();
   const { setSidebarOpen } = useUIStore();
 
@@ -22,10 +20,11 @@ export function useSidebarNavigation() {
     }
   }, [setSidebarOpen]);
 
-  const handleLogout = useCallback(() => {
-    logout();
-    navigate('/login');
-  }, [logout, navigate]);
+  const handleLogout = useCallback(async () => {
+    await logout();
+    // Full page redirect ensures clean state (clears any stale React/Query cache)
+    window.location.href = '/login';
+  }, [logout]);
 
   return {
     handleMobileNav,