feat: update AuthButton and Header for improved user experience

- Increased avatar and icon sizes in `AuthButton` for better visibility.
- Integrated session handling in `Header` to display user profile link and sign-out button when authenticated, enhancing mobile menu functionality.
- Refactored mobile menu overlay to a modal for improved usability.

src/components/AuthButton.tsx

@@ -41,10 +41,10 @@ export function AuthButton() {
           <img 
             src={session.user.avatar} 
             alt="Avatar" 
-            className="w-4 h-4 rounded-full object-cover"
+            className="w-10 h-10 rounded-full object-cover"
           />
         ) : (
-          <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+          <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
             <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M16 7a4 4 0 11-8 0 4 4 0 018 0zM12 14a7 7 0 00-7 7h14a7 7 0 00-7-7z" />
           </svg>
         )}

src/components/ui/Header.tsx

@@ -9,6 +9,7 @@ import { Theme } from '@/lib/theme-config';
 import { THEME_CONFIG, getThemeMetadata } from '@/lib/theme-config';
 import { useKeyboardShortcutsModal } from '@/contexts/KeyboardShortcutsContext';
 import { AuthButton } from '@/components/AuthButton';
+import { useSession, signOut } from 'next-auth/react';
 
 interface HeaderProps {
   title?: string;
@@ -23,6 +24,7 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
   const [mobileMenuOpen, setMobileMenuOpen] = useState(false);
   const [themeDropdownOpen, setThemeDropdownOpen] = useState(false);
   const { openModal: openShortcutsModal } = useKeyboardShortcutsModal();
+  const { data: session } = useSession();
 
   // Liste des thèmes disponibles avec leurs labels et icônes
   const themes: { value: Theme; label: string; icon: string }[] = THEME_CONFIG.allThemes.map(themeValue => {
@@ -76,7 +78,7 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
   ];
 
   return (
-    <header className="relative z-50 bg-[var(--card)]/80 backdrop-blur-sm border-b border-[var(--border)]/50 shadow-lg shadow-[var(--card)]/20">
+    <header className="relative z-50 bg-[var(--card)]/80 border-b border-[var(--border)]/50 shadow-lg shadow-[var(--card)]/20">
       <div className="container mx-auto px-4 sm:px-6 py-4">
         {/* Layout mobile/tablette */}
         <div className="lg:hidden">
@@ -284,17 +286,18 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
 
       </div>
 
-      {/* Menu mobile/tablette en overlay fixe */}
+      {/* Menu mobile/tablette en modal */}
       {mobileMenuOpen && (
-        <>
+        <div className="lg:hidden fixed inset-0 z-[9999] flex items-start justify-center pt-20">
-          {/* Backdrop pour fermer le menu */}
+          {/* Backdrop */}
           <div 
-            className="lg:hidden fixed inset-0 bg-black/20 backdrop-blur-sm z-[100]"
+            className="absolute inset-0 bg-black/50"
             onClick={() => setMobileMenuOpen(false)}
           />
-          {/* Menu */}
+          
-          <div className="lg:hidden fixed top-[80px] left-0 right-0 bg-[var(--card)]/98 backdrop-blur-md border-b border-[var(--border)]/50 shadow-xl z-[101]">
+          {/* Modal content */}
-            <nav className="container mx-auto px-4 py-6">
+          <div className="relative bg-[var(--card)] border border-[var(--border)] rounded-lg shadow-xl mx-4 w-full max-w-sm">
+            <nav className="p-6">
               <div className="space-y-3">
                 {navLinks.map(({ href, label }) => (
                   <Link
@@ -306,10 +309,37 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
                     {label}
                   </Link>
                 ))}
+                
+                {/* Séparateur */}
+                {session && (
+                  <>
+                    <div className="border-t border-[var(--border)]/30 my-4"></div>
+                    
+                    {/* Lien profil */}
+                    <Link
+                      href="/profile"
+                      className={getMobileLinkClasses('/profile')}
+                      onClick={() => setMobileMenuOpen(false)}
+                    >
+                      👤 Profil
+                    </Link>
+                    
+                    {/* Bouton déconnexion */}
+                    <button
+                      onClick={() => {
+                        signOut({ callbackUrl: '/login' });
+                        setMobileMenuOpen(false);
+                      }}
+                      className="font-mono text-sm uppercase tracking-wider transition-colors px-4 py-3 rounded-md block w-full text-left text-[var(--destructive)] hover:text-[var(--destructive)] hover:bg-[var(--destructive)]/10"
+                    >
+                      🚪 Déconnexion
+                    </button>
+                  </>
+                )}
               </div>
             </nav>
           </div>
-        </>
+        </div>
       )}
     </header>
   );