feat: Convert email date format from American to European (dd.mm.yyyy)

- Add formatDateGerman() helper function to convert yyyy-mm-dd to dd.mm.yyyy
- Update all email templates (HTML and text versions) to use European date format
- Apply formatting to booking pending, confirmed, and cancelled emails
- Ensure consistent date display across all customer communications
- Improve user experience with familiar German date format

Changes:
- email-templates.ts: Add date formatting to all HTML templates
- bookings.ts: Add date formatting to all text email versions
- Both files: Consistent European date format (dd.mm.yyyy) throughout

src/client/components/booking-form.tsx

@@ -10,6 +10,7 @@ export function BookingForm() {
   const [appointmentDate, setAppointmentDate] = useState("");
   const [selectedSlotId, setSelectedSlotId] = useState<string>("");
   const [notes, setNotes] = useState("");
+  const [agbAccepted, setAgbAccepted] = useState(false);
 
   const { data: treatments } = useQuery(
     queryClient.treatments.live.list.experimental_liveOptions()
@@ -38,6 +39,10 @@ export function BookingForm() {
       alert("Bitte fülle alle erforderlichen Felder aus");
       return;
     }
+    if (!agbAccepted) {
+      alert("Bitte bestätige die Kenntnisnahme der Allgemeinen Geschäftsbedingungen");
+      return;
+    }
     const slot = availableSlots.find((s) => s.id === selectedSlotId);
     const appointmentTime = slot?.time || "";
     createBooking(
@@ -60,6 +65,7 @@ export function BookingForm() {
           setAppointmentDate("");
           setSelectedSlotId("");
           setNotes("");
+          setAgbAccepted(false);
           alert("Buchung erfolgreich erstellt! Wir werden dich kontaktieren, um deinen Termin zu bestätigen.");
         },
       }
@@ -88,7 +94,7 @@ export function BookingForm() {
             <option value="">Wähle eine Behandlung</option>
             {treatments?.map((treatment) => (
               <option key={treatment.id} value={treatment.id}>
-                {treatment.name} - ${(treatment.price / 100).toFixed(2)} ({treatment.duration} min)
+                {treatment.name} - {(treatment.price / 100).toFixed(2)} € ({treatment.duration} Min)
               </option>
             ))}
           </select>
@@ -196,6 +202,35 @@ export function BookingForm() {
           />
         </div>
 
+        {/* AGB Acceptance */}
+        <div className="bg-gray-50 border border-gray-200 rounded-lg p-4">
+          <div className="flex items-start space-x-3">
+            <input
+              type="checkbox"
+              id="agb-acceptance"
+              checked={agbAccepted}
+              onChange={(e) => setAgbAccepted(e.target.checked)}
+              className="mt-1 h-4 w-4 text-pink-600 focus:ring-pink-500 border-gray-300 rounded"
+              required
+            />
+            <div className="flex-1">
+              <label htmlFor="agb-acceptance" className="text-sm font-medium text-gray-700 cursor-pointer">
+                Ich habe die <a 
+                  href="/AGB.pdf" 
+                  target="_blank" 
+                  rel="noopener noreferrer"
+                  className="text-pink-600 hover:text-pink-700 underline font-semibold"
+                >
+                  Allgemeinen Geschäftsbedingungen (AGB)
+                </a> gelesen und akzeptiere diese *
+              </label>
+              <p className="text-xs text-gray-500 mt-1">
+                📋 Die AGB enthalten wichtige Informationen zu Buchungsgebühren, Stornierungsregeln und unseren Serviceleistungen.
+              </p>
+            </div>
+          </div>
+        </div>
+
         <button
           type="submit"
           disabled={isPending}