style(subscription): adjust back button spacing

src/app/subscription/components/subscription-back-link.tsx

@@ -3,10 +3,11 @@
  * 订阅页返回箭头
  *
  * 视觉规格（与设计稿对齐）：
- *   - 24×24 SVG chevron-left
+ *   - 24×24 chevron-left 图标
  *   - 黑色，2px 描边
  *   - 无 "Back" 文本
  */
+import { ChevronLeft } from "lucide-react";
 import Link from "next/link";
 
 import { ROUTES } from "@/router/routes";
@@ -24,22 +25,12 @@ export function SubscriptionBackLink({ className }: SubscriptionBackLinkProps) {
       aria-label="Back"
       className={[styles.backLink, className].filter(Boolean).join(" ")}
     >
-      <svg
-        width="24"
-        height="24"
-        viewBox="0 0 24 24"
-        fill="none"
+      <ChevronLeft
+        size={24}
+        strokeWidth={2}
         aria-hidden="true"
         className={styles.icon}
-      >
-        <path
-          d="M15 6l-6 6 6 6"
-          stroke="currentColor"
-          strokeWidth="2"
-          strokeLinecap="round"
-          strokeLinejoin="round"
-        />
-      </svg>
+      />
     </Link>
   );
 }

src/app/subscription/components/subscription-screen.module.css

@@ -3,14 +3,13 @@
   flex-direction: column;
   min-height: 100dvh;
   background: var(--color-page-background);
-  padding: 30px 30px 10px;
+  padding: 18 30px 10px;
 }
 
 .header {
   display: flex;
   align-items: center;
   height: 40px;
-  padding-top: var(--spacing-sm);
 }
 
 .backSlot {