style(mine): Add decorative gradient overlays to profile header

- Add overflow hidden property to contain pseudo-elements
- Add ::before pseudo-element with radial gradient circle overlay positioned at top-right
- Add ::after pseudo-element with radial gradient circle overlay positioned at bottom-left
- Enhance visual depth and modern aesthetic of profile header section

assets/css/mine/index.scss

@@ -16,6 +16,29 @@
       height: 148rpx;
       background: linear-gradient(135deg, #2563eb 0%, #3b82f6 100%);
       border-radius: 0 0 32rpx 32rpx;
+      overflow: hidden;
+
+      &::before {
+        content: '';
+        position: absolute;
+        top: -50%;
+        right: -20%;
+        width: 200rpx;
+        height: 200rpx;
+        background: radial-gradient(circle, rgba(255, 255, 255, 0.15) 0%, transparent 70%);
+        border-radius: 50%;
+      }
+
+      &::after {
+        content: '';
+        position: absolute;
+        bottom: -30%;
+        left: -10%;
+        width: 160rpx;
+        height: 160rpx;
+        background: radial-gradient(circle, rgba(255, 255, 255, 0.1) 0%, transparent 70%);
+        border-radius: 50%;
+      }
     }
 
     .profile-card {