feat: restore credit limits and harden SMS sending

src/apps/client/ClientBillingPage.tsx

@@ -7,6 +7,7 @@ import { formatDateTime } from '@/utils/dateTime';
 
 export function ClientBillingPage() {
   const [balanceCents, setBalanceCents] = useState(0);
+  const [creditCents, setCreditCents] = useState(0);
   const [orders, setOrders] = useState<RechargeOrder[]>([]);
   const [page, setPage] = useState(1);
   const [loading, setLoading] = useState(true);
@@ -21,6 +22,7 @@ export function ClientBillingPage() {
     Promise.all([clientApi.getDashboard(), clientApi.listOrders()])
       .then(([dashboard, nextOrders]) => {
         setBalanceCents(dashboard.accounts[0]?.balanceCents ?? 0);
+        setCreditCents(dashboard.accounts[0]?.creditCents ?? 0);
         setOrders(nextOrders);
         setError('');
       })
@@ -36,7 +38,11 @@ export function ClientBillingPage() {
       <div className="dashboard-grid enterprise-summary-grid">
         <div className="surface mini-status-card">
           <WalletCards size={22} />
-          <div><span>当前可用余额</span><strong>¥{formatCents(balanceCents)}</strong><small>短信发送仅按现金余额校验。</small></div>
+          <div><span>现金余额</span><strong>¥{formatCents(balanceCents)}</strong><small>充值和扣费后的账面余额。</small></div>
+        </div>
+        <div className="surface mini-status-card">
+          <WalletCards size={22} />
+          <div><span>可用发送额度</span><strong>¥{formatCents(balanceCents + creditCents)}</strong><small>大于 0 时可以发送短信。</small></div>
         </div>
       </div>
       <div className="surface section-stack">

src/apps/client/ClientHome.tsx

@@ -50,7 +50,7 @@ export function ClientHome() {
   }, []);
 
   const account = dashboard?.accounts[0];
-  const availableBalance = (account?.balanceCents ?? 0) / 100;
+  const availableBalance = ((account?.balanceCents ?? 0) + (account?.creditCents ?? 0)) / 100;
   const todaySpend = (dashboard?.today.spendCents ?? 0) / 100;
   const todayRefund = Math.abs((dashboard?.transactions._sum.amountCents ?? 0) < 0 ? 0 : dashboard?.transactions._sum.amountCents ?? 0) / 100;
   const balanceBaseline = Math.max(availableBalance + todaySpend - todayRefund, availableBalance, 1);
@@ -102,9 +102,9 @@ export function ClientHome() {
 
       <div className="dashboard-grid">
         <div className="surface metric-card metric-card--featured">
-          <span>账户剩余余额</span>
+          <span>可用发送额度</span>
           <strong>¥{formatAmount(availableBalance)}</strong>
-          <small>今日消费 ¥{formatAmount(todaySpend)}</small>
+          <small>现金余额 ¥{formatCents(account?.balanceCents)}</small>
         </div>
         <div className="surface metric-card">
           <span>今日发送</span>