refactor: 将 @iconify/vue 图标替换为 lucide-vue-next 本地组件

- 所有 lucide: 前缀的图标字符串替换为 lucide-vue-next 组件直接引用
- 动态图标绑定改为 <component :is> 渲染
- h(Icon, { icon: 'lucide:xxx' }) 改为 h(Xxx, { class: ... })
- app-card.vue 的 icon_url 改为 <img> 标签（实际是图片路径）
- 修复 Webhook 标识符冲突（重命名为 WebhookIcon）
- payment-channels 保留 @iconify/vue 用于品牌图标（支付宝、微信、Stripe、PayPal、USDT）

frontend/src/pages/auth/register.vue

@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import { Icon } from '@iconify/vue'
+import { Check, Loader2, ShieldCheck } from 'lucide-vue-next'
 import { computed, ref } from 'vue'
 import { useRouter } from 'vue-router'
 import { toast } from 'vue-sonner'
@@ -82,7 +82,7 @@ async function handleRegister() {
       <div class="relative z-10 flex flex-col justify-center px-12">
         <div class="flex items-center gap-3 mb-8">
           <div class="size-12 rounded-xl bg-primary flex items-center justify-center">
-            <Icon icon="lucide:shield-check" class="size-7 text-primary-foreground" />
+            <ShieldCheck class="size-7 text-primary-foreground" />
           </div>
           <span class="text-2xl font-bold">管理平台</span>
         </div>
@@ -95,19 +95,19 @@ async function handleRegister() {
         <div class="space-y-4">
           <div class="flex items-center gap-3">
             <div class="size-8 rounded-full bg-primary/20 flex items-center justify-center">
-              <Icon icon="lucide:check" class="size-4 text-primary" />
+              <Check class="size-4 text-primary" />
             </div>
             <span>免费创建应用，快速集成 SDK</span>
           </div>
           <div class="flex items-center gap-3">
             <div class="size-8 rounded-full bg-primary/20 flex items-center justify-center">
-              <Icon icon="lucide:check" class="size-4 text-primary" />
+              <Check class="size-4 text-primary" />
             </div>
             <span>完善的用户管理和数据分析</span>
           </div>
           <div class="flex items-center gap-3">
             <div class="size-8 rounded-full bg-primary/20 flex items-center justify-center">
-              <Icon icon="lucide:check" class="size-4 text-primary" />
+              <Check class="size-4 text-primary" />
             </div>
             <span>灵活的卡密授权方案</span>
           </div>
@@ -120,7 +120,7 @@ async function handleRegister() {
         <div class="text-center mb-8 lg:hidden">
           <div class="flex items-center justify-center gap-3 mb-4">
             <div class="size-10 rounded-xl bg-primary flex items-center justify-center">
-              <Icon icon="lucide:shield-check" class="size-6 text-primary-foreground" />
+              <ShieldCheck class="size-6 text-primary-foreground" />
             </div>
             <span class="text-xl font-bold">管理平台</span>
           </div>
@@ -198,7 +198,7 @@ async function handleRegister() {
             class="w-full"
             :disabled="loading || !isValid"
           >
-            <Icon v-if="loading" icon="lucide:loader-2" class="mr-2 h-4 w-4 animate-spin" />
+            <Loader2 v-if="loading" class="mr-2 h-4 w-4 animate-spin" />
             {{ loading ? '注册中...' : '注册' }}
           </UiButton>
         </form>