feat: replace SVGs with lucide-react icons across components

- Updated ProfilePage, AuthButton, RecentTasks, WelcomeSection, DesktopControls, MobileControls, and various Kanban components to use lucide-react icons instead of SVGs for improved consistency and maintainability.
- Icons replaced include Check, User, Mail, Calendar, Shield, Save, X, Loader2, Filter, Target, List, Grid3X3, ChevronDown, ChevronRight, Edit, Trash2, and Plus.

src/components/AuthButton.tsx

@@ -3,6 +3,7 @@
 import { useSession, signOut } from 'next-auth/react'
 import { useRouter } from 'next/navigation'
 import { Button } from '@/components/ui/Button'
+import { User, LogOut } from 'lucide-react'
 
 export function AuthButton() {
   const { data: session, status } = useSession()
@@ -44,9 +45,7 @@ export function AuthButton() {
             className="w-10 h-10 rounded-full object-cover"
           />
         ) : (
-          <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>
+          <User className="w-6 h-6" />
         )}
       </Button>
       <Button
@@ -56,9 +55,7 @@ export function AuthButton() {
         className="p-1 h-auto"
         title="Déconnexion"
       >
-        <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
-          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M17 16l4-4m0 0l-4-4m4 4H7m6 4v1a3 3 0 01-3 3H6a3 3 0 01-3-3V7a3 3 0 013-3h4a3 3 0 013 3v1" />
-        </svg>
+        <LogOut className="w-4 h-4" />
       </Button>
     </div>
   )