feat: Implement client authentication and pre-fill functionality

- Added AuthController for client login and token management.
- Introduced AuthGate for handling authentication state and login UI.
- Updated API to support fetching client data for pre-filling forms.
- Modified App.vue to pre-fill client information if logged in.
- Enhanced client model to include username and password fields.
- Created migration for adding username and password to clients table.
- Added utility for generating secure usernames and passwords.
- Updated frontend to handle client tokens for pre-filling checkout forms.
- Removed old CSS file and updated HTML references to new assets.
- Added StatsOverview widget for displaying client and quote statistics.
- Improved error handling and user feedback in the login process.

backoffice/app/Filament/Widgets/StatsOverview.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Filament\Widgets;
+
+use App\Filament\Resources\ClienteResource;
+use App\Filament\Resources\PreventivoResource;
+use App\Models\Cliente;
+use App\Models\Preventivo;
+use Filament\Widgets\StatsOverviewWidget as BaseWidget;
+use Filament\Widgets\StatsOverviewWidget\Stat;
+
+class StatsOverview extends BaseWidget
+{
+    protected function getStats(): array
+    {
+        return [
+            Stat::make('Preventivi', Preventivo::count())
+                ->icon('heroicon-o-document-text')
+                ->color('warning')
+                ->url(PreventivoResource::getUrl('index')),
+            Stat::make('Clienti', Cliente::count())
+                ->icon('heroicon-o-users')
+                ->color('success')
+                ->url(ClienteResource::getUrl('index')),
+        ];
+    }
+}