feat: add customer email functionality for booking confirmations

- Implemented email confirmation for admin and public bookings.
- Added customerEmail field to booking schemas and services.
- Created email templates for booking confirmation, cancellation, and no-show notifications.
- Updated booking handlers to send emails upon booking creation and status updates.
- Enhanced frontend forms to capture customer email during booking creation.

apps/frontend/src/features/public-booking/public-booking-page.tsx

@@ -62,6 +62,7 @@ const bookingFormSchema = z.object({
     .trim()
     .min(6, 'Ingresá un teléfono válido.')
     .max(30, 'El teléfono no puede superar los 30 caracteres.'),
+  customerEmail: z.string().email('Ingresá un email válido.').optional().or(z.literal('')),
 });
 
 type BookingFormValues = z.infer<typeof bookingFormSchema>;
@@ -1294,6 +1295,24 @@ function SelectedSlotCard(props: BookingShellProps & { compact?: boolean }) {
             </Field>
           </div>
 
+          <Field data-invalid={Boolean(errors.customerEmail)}>
+            <FieldLabel htmlFor="customerEmail" className="text-white/76">
+              Email <span className="text-white/40 font-normal">(opcional)</span>
+            </FieldLabel>
+            <Input
+              id="customerEmail"
+              type="email"
+              placeholder="Ej: juan@ejemplo.com"
+              aria-invalid={Boolean(errors.customerEmail)}
+              className="border-white/10 bg-white/[0.045] text-white placeholder:text-white/32"
+              {...register('customerEmail')}
+            />
+            <p className="mt-1 text-xs text-white/40">
+              Te enviaremos la confirmación de la reserva por email.
+            </p>
+            <FieldError errors={[errors.customerEmail]} />
+          </Field>
+
           {createError && <p className="text-sm text-red-300">{createError}</p>}
           {navigationError && <p className="text-sm text-red-300">{navigationError}</p>}
 
@@ -1409,6 +1428,7 @@ export function PublicBookingPage({ complexSlug }: PublicBookingPageProps) {
     defaultValues: {
       customerName: '',
       customerPhone: '',
+      customerEmail: '',
     },
   });
 
@@ -1425,6 +1445,7 @@ export function PublicBookingPage({ complexSlug }: PublicBookingPageProps) {
         startTime: selectedSlot.startTime,
         customerName: payload.customerName,
         customerPhone: payload.customerPhone,
+        customerEmail: payload.customerEmail || undefined,
       });
     },
   });