refactor: 奖品卡片仅展示说明文案，移动端隐藏库存显示

- StampPopup / RedeemModal 的 Reward 卡片去掉 prize.name 行，
  将 description 作为主要文案展示
- 移动端 RedeemModal 隐藏「剩余库存 X 枚」与「奖品库存已耗尽」
  文案，库存扣减与 sold-out 状态的后端逻辑保持不变
- 确认兑换弹窗内的 Reward 卡片同步调整

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/web/src/components/RedeemModal.tsx

@@ -150,21 +150,12 @@ export default function RedeemModal({ stamp, onRedeem, onClose }: RedeemModalPro
         {/* Prize card */}
         {prize ? (
           <div className="rounded-xl border border-[var(--jade)] bg-[rgba(45,106,79,0.05)] p-4 mb-4">
-            <p className="text-[10px] tracking-[0.2em] text-[var(--jade)] uppercase mb-1.5">Reward</p>
-            <p className="text-sm font-semibold text-[var(--text-primary)]">{prize.name}</p>
-            {prize.description && (
-              <p className="text-xs text-[var(--text-muted)] mt-1 leading-relaxed">{prize.description}</p>
+            <p className="text-[10px] tracking-[0.2em] text-[var(--jade)] uppercase mb-2">Reward</p>
+            {prize.description ? (
+              <p className="text-sm text-[var(--text-primary)] leading-relaxed">{prize.description}</p>
+            ) : (
+              <p className="text-sm text-[var(--text-muted)]">暂未填写权益说明</p>
             )}
-            <div className="mt-3 pt-3 border-t border-[var(--jade)]/15 flex items-baseline justify-between">
-              <span className="text-xs text-[var(--text-muted)]">剩余库存</span>
-              <span
-                className="text-xl font-semibold"
-                style={{ color: prize.stock > 0 ? "var(--jade)" : "var(--terracotta)" }}
-              >
-                {prize.stock}
-                <span className="text-xs font-normal text-[var(--text-muted)] ml-1">枚</span>
-              </span>
-            </div>
           </div>
         ) : (
           <div className="rounded-xl border border-[var(--border-muted)] bg-white p-4 mb-4 text-center">
@@ -180,9 +171,6 @@ export default function RedeemModal({ stamp, onRedeem, onClose }: RedeemModalPro
         {mode === "redeemed" && (
           <p className="text-xs text-[var(--text-muted)] text-center mb-4">你已经兑换过这枚图章对应的奖品</p>
         )}
-        {mode === "sold-out" && (
-          <p className="text-xs text-[var(--terracotta)] text-center mb-4">奖品库存已耗尽</p>
-        )}
 
         {error && <p className="text-sm text-[var(--terracotta)] mb-3 text-center">{error}</p>}
 
@@ -238,10 +226,9 @@ export default function RedeemModal({ stamp, onRedeem, onClose }: RedeemModalPro
               <h3 className="text-base font-semibold text-[var(--text-primary)] mb-4">确认兑换</h3>
 
               <div className="rounded-xl border border-[var(--jade)] bg-[rgba(45,106,79,0.05)] p-3.5 mb-3">
-                <p className="text-[10px] tracking-[0.2em] text-[var(--jade)] uppercase mb-1">Reward</p>
-                <p className="text-sm font-semibold text-[var(--text-primary)]">{prize.name}</p>
+                <p className="text-[10px] tracking-[0.2em] text-[var(--jade)] uppercase mb-2">Reward</p>
                 {prize.description && (
-                  <p className="text-xs text-[var(--text-muted)] mt-0.5">{prize.description}</p>
+                  <p className="text-sm text-[var(--text-primary)] leading-relaxed">{prize.description}</p>
                 )}
               </div>
 

packages/web/src/components/StampPopup.tsx

@@ -49,13 +49,10 @@ export default function StampPopup({ name, imageColor, note, prize, status, onCo
         {note && <p className="text-xs text-[var(--text-muted)] mb-3 leading-relaxed">{note}</p>}
 
         {/* Prize rule (preview only) */}
-        {status === "preview" && prize && (
+        {status === "preview" && prize?.description && (
           <div className="mt-3 mb-1 rounded-xl border border-[var(--jade)] bg-[rgba(45,106,79,0.05)] p-3.5 text-left">
-            <p className="text-[10px] tracking-[0.2em] text-[var(--jade)] uppercase mb-1">Reward</p>
-            <p className="text-sm font-semibold text-[var(--text-primary)]">{prize.name}</p>
-            {prize.description && (
-              <p className="text-xs text-[var(--text-secondary)] mt-1 leading-relaxed">{prize.description}</p>
-            )}
+            <p className="text-[10px] tracking-[0.2em] text-[var(--jade)] uppercase mb-2">Reward</p>
+            <p className="text-sm text-[var(--text-primary)] leading-relaxed">{prize.description}</p>
           </div>
         )}