feat: add authentication support and user model

- Updated `env.example` to include NextAuth configuration for authentication.
- Added `next-auth` dependency to manage user sessions.
- Introduced `User` model in Prisma schema with fields for user details and password hashing.
- Integrated `AuthProvider` in layout for session management across the app.
- Enhanced `Header` component with `AuthButton` for user authentication controls.

src/components/ui/Header.tsx

@@ -8,6 +8,7 @@ import { useState } from 'react';
 import { Theme } from '@/lib/theme-config';
 import { THEME_CONFIG, getThemeMetadata } from '@/lib/theme-config';
 import { useKeyboardShortcutsModal } from '@/contexts/KeyboardShortcutsContext';
+import { AuthButton } from '@/components/AuthButton';
 
 interface HeaderProps {
   title?: string;
@@ -173,6 +174,12 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
                 )}
               </button>
             </div>
+
+          </div>
+
+          {/* Auth controls à droite mobile */}
+          <div className="flex items-center gap-1">
+            <AuthButton />
           </div>
         </div>
 
@@ -264,9 +271,15 @@ export function Header({ title = "TowerControl", subtitle = "Task Management", s
                   </>
                 )}
               </div>
+
             </nav>
           </div>
 
+          {/* Contrôles à droite */}
+          <div className="flex items-center gap-2">
+            <AuthButton />
+          </div>
+
         </div>
 
       </div>