Add PayPal/Stripe toggle in admin settings

Payment methods can now be enabled/disabled under Einstellungen → Zahlungsarten.
Warning shown if API keys are missing in .env.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

resources/views/admin/settings/index.blade.php

@@ -105,6 +105,29 @@
             </div>
         </div>
 
+        {{-- Zahlungsarten --}}
+        <div class="bg-white rounded shadow p-6">
+            <h3 class="font-semibold mb-4">Zahlungsarten</h3>
+            <div class="space-y-3">
+                <label class="flex items-center gap-2 text-sm">
+                    <input type="checkbox" name="payment_paypal_enabled" value="1"
+                           {{ ($settings['payment_paypal_enabled'] ?? false) ? 'checked' : '' }}>
+                    <span>PayPal aktivieren</span>
+                    @if(!config('paypal.live.client_id') && !config('paypal.sandbox.client_id'))
+                        <span class="text-xs text-orange-500">(PAYPAL_LIVE_CLIENT_ID in .env fehlt)</span>
+                    @endif
+                </label>
+                <label class="flex items-center gap-2 text-sm">
+                    <input type="checkbox" name="payment_stripe_enabled" value="1"
+                           {{ ($settings['payment_stripe_enabled'] ?? false) ? 'checked' : '' }}>
+                    <span>Kreditkarte via Stripe aktivieren</span>
+                    @if(!config('services.stripe.key'))
+                        <span class="text-xs text-orange-500">(STRIPE_KEY in .env fehlt)</span>
+                    @endif
+                </label>
+            </div>
+        </div>
+
         {{-- Design / Theme --}}
         <div class="bg-white rounded shadow p-6">
             <h3 class="font-semibold mb-4">Design</h3>