💄 style(index): optimize image display and layout structure

- remove unnecessary mode attribute from Image components to use default layout
- change text-center container to flex layout with centered items for better alignment
- adjust login prompt image and text layout for more balanced visual presentation

mini/src/pages/index/index.tsx

@@ -65,7 +65,6 @@ export default function Index() {
                 <Image
                   className="w-full h-full"
                   src={user.avatar || 'https://images.unsplash.com/photo-1494790108755-2616b612b786?w=160&h=160&fit=crop&crop=face'}
-                  // mode="aspectFill"
                 />
               </View>
               <View>
@@ -122,11 +121,10 @@ export default function Index() {
         </View>
       ) : (
         <View className="p-6">
-          <View className="text-center mb-8">
+          <View className="flex flex-col items-center mb-8">
             <Image
               className="w-32 h-32 rounded-full mx-auto mb-4"
               src="https://images.unsplash.com/photo-1551650975-87deedd944c3?w=192&h=192&fit=crop"
-              mode="aspectFit"
             />
             <Text className="text-3xl font-bold text-gray-900 mb-2">欢迎使用小程序</Text>
             <Text className="text-gray-600 text-lg">请先登录以使用完整功能</Text>