Simplify self-service payments to full-amount checkout, add manual-page payment tab

Self-service "pay now" flows (registration success + user dashboard) now go
straight to a Yoco checkout for the full outstanding balance instead of
prompting for a partial amount; that page has been removed. Partial-amount
payment links remain supervisor/admin-only via the Payments dashboard.

Also adds a "Record Payment" tab to the supervisor manual registration page,
pre-filled with the most recently created registration, so staff can capture
a payment right after registering someone without leaving the page.

frontend/src/app/dashboard/user/page.tsx

@@ -1,7 +1,7 @@
 "use client";
 import React, { useEffect, useMemo, useState } from "react";
 import { useAuth } from "@/hooks/useAuth";
-import { apiFetch } from "@/lib/api";
+import { apiFetch, createFullPaymentCheckout } from "@/lib/api";
 import { useRouter } from "next/navigation";
 import { formatDate } from "@/lib/date";
 import { formatPaymentMethod } from "@/lib/paymentMethod";
@@ -312,6 +312,41 @@ export default function UserDashboardPage() {
     }
   };
 
+  // Creates a Yoco checkout for the full outstanding balance and redirects there directly —
+  // choosing a partial amount is only available from the supervisor payments dashboard.
+  const payNow = async (registrationId: string) => {
+    if (!token) return;
+    setError(null);
+    setInfo(null);
+    setDialog({ open: true, message: "Creating payment link…", loading: true });
+    try {
+      const res = await createFullPaymentCheckout(token, registrationId);
+      if (res.priceUpdated) {
+        setDialog({ open: false, message: "", loading: false });
+        setError(`${res.message || 'Pricing has changed.'} New total: R ${(res.newTotal ?? 0).toFixed(2)}. Please try again.`);
+        // Refresh this registration's billing so the displayed outstanding reflects the new price
+        try {
+          const now = new Date();
+          const r = await apiFetch<any>(`/api/registrations/${encodeURIComponent(registrationId)}`, { authToken: token });
+          const pays = await apiFetch<any[]>(`/api/payments/registration/${encodeURIComponent(registrationId)}`, { authToken: token });
+          const totalPaid = pays.reduce((s, p) => s + (p.amount || 0), 0);
+          const totalDue = (r.registrationOptions || []).reduce((sum: number, opt: any) => sum + optionUnitPrice(opt, null, now) * (opt.quantity || 0), 0);
+          setBilling(prev => ({ ...prev, [registrationId]: { totalDue, totalPaid, outstanding: Math.max(0, totalDue - totalPaid), payments: pays } }));
+        } catch {}
+        return;
+      }
+      if (!res.redirectUrl) {
+        setDialog({ open: false, message: "", loading: false });
+        setError("Failed to create checkout");
+        return;
+      }
+      window.location.href = res.redirectUrl;
+    } catch (e: any) {
+      setDialog({ open: false, message: "", loading: false });
+      setError(e?.message || "Failed to create checkout");
+    }
+  };
+
   // Print helpers
   const buildTicketHtmlCard = (t: any, buyerName?: string) => {
     const eventTitle = t.event?.title || t.eventId || "Event";
@@ -1039,7 +1074,7 @@ export default function UserDashboardPage() {
                 {canModifyActive && activeBill && activeBill.outstanding > 0 ? (
                   <button
                     className="px-3 py-1.5 text-sm bg-green-600 text-white rounded hover:bg-green-700 shadow-sm focus:outline-none focus:ring-2 focus:ring-green-500 focus:ring-offset-1"
-                    onClick={() => router.push(`/dashboard/user/pay?registrationId=${encodeURIComponent(activeReg.id)}`)}
+                    onClick={() => payNow(activeReg.id)}
                   >Make payment</button>
                 ) : (
                   <>