feat: 画风选择卡片用静态图片替换 emoji 占位，支持选中/未选中状态切换

- 导入 8 张画风图片（卡通/水彩/水墨/彩铅 × 选中/未选中）
- 根据选中状态动态切换预览图
- 删除 emoji SVG fallback 逻辑
- 隐藏油画、剪贴画（hidden: true）

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/public/create/views/StyleSelectView.vue

@@ -1,3 +1,6 @@
+<script lang="ts">
+export default { name: 'StyleSelectView' }
+</script>
 <template>
   <div class="style-page page-fullscreen">
     <PageHeader title="选择画风" subtitle="为绘本挑选一种你喜欢的画风" :step="3" />
@@ -11,7 +14,7 @@
 
       <div class="style-grid">
         <div
-          v-for="s in styles"
+          v-for="s in visibleStyles"
           :key="s.styleId"
           class="style-card"
           :class="{ selected: selected === s.styleId }"
@@ -24,10 +27,9 @@
 
           <div class="style-preview">
             <img
-              :src="previewUrl(s.styleId)"
+              :src="selected === s.styleId ? s.imgActive : s.img"
               :alt="s.styleName"
               class="style-preview-img"
-              @error="(e) => onPreviewError(e, s.hue)"
             />
           </div>
           <div class="style-info">
@@ -58,6 +60,16 @@ import {
 import PageHeader from '@/components/aicreate/PageHeader.vue'
 import { useAicreateStore } from '@/stores/aicreate'
 
+// 导入画风图片：{style}-normal.png 未选中，{style}-active.png 选中
+import styleCartoonNormal from '@/assets/images/style-cartoon-normal.png'
+import styleCartoonActive from '@/assets/images/style-cartoon-active.png'
+import styleWatercolorNormal from '@/assets/images/style-watercolor-normal.png'
+import styleWatercolorActive from '@/assets/images/style-watercolor-active.png'
+import styleInkNormal from '@/assets/images/style-ink-normal.png'
+import styleInkActive from '@/assets/images/style-ink-active.png'
+import stylePencilNormal from '@/assets/images/style-pencil-normal.png'
+import stylePencilActive from '@/assets/images/style-pencil-active.png'
+
 const router = useRouter()
 const store = useAicreateStore()
 const selected = ref('')
@@ -66,40 +78,26 @@ interface StyleItem {
   styleId: string
   styleName: string
   desc: string
-  /** 用于预览图加载失败时的 fallback 渐变色调（HSL 色相） */
-  hue: number
+  /** 未选中态图片 */
+  img: string
+  /** 选中态图片 */
+  imgActive: string
+  /** hidden=true 时暂不展示，后续开发开放 */
+  hidden?: boolean
 }
 
 const styles: StyleItem[] = [
-  { styleId: 'style_cartoon',    styleName: '卡通风格', desc: '色彩鲜明，充满童趣', hue: 30  },
-  { styleId: 'style_watercolor', styleName: '水彩风格', desc: '柔和透明，梦幻浪漫', hue: 200 },
-  { styleId: 'style_ink',        styleName: '水墨国风', desc: '古韵悠长，意境深远', hue: 270 },
-  { styleId: 'style_pencil',     styleName: '彩铅风格', desc: '细腻温暖，自然亲切', hue: 50  },
-  { styleId: 'style_oilpaint',   styleName: '油画风格', desc: '色彩浓郁，质感丰富', hue: 25  },
-  { styleId: 'style_collage',    styleName: '剪贴画',   desc: '趣味拼贴，创意满满', hue: 320 },
+  { styleId: 'style_cartoon',    styleName: '卡通风格', desc: '色彩鲜明，充满童趣', img: styleCartoonNormal,    imgActive: styleCartoonActive },
+  { styleId: 'style_watercolor', styleName: '水彩风格', desc: '柔和透明，梦幻浪漫', img: styleWatercolorNormal, imgActive: styleWatercolorActive },
+  { styleId: 'style_ink',        styleName: '水墨国风', desc: '古韵悠长，意境深远', img: styleInkNormal,        imgActive: styleInkActive },
+  { styleId: 'style_pencil',     styleName: '彩铅风格', desc: '细腻温暖，自然亲切', img: stylePencilNormal,     imgActive: stylePencilActive },
+  // 油画、剪贴画暂不开放，后续开发后去掉 hidden 即可
+  { styleId: 'style_oilpaint',   styleName: '油画风格', desc: '色彩浓郁，质感丰富', img: '', imgActive: '', hidden: true },
+  { styleId: 'style_collage',    styleName: '剪贴画',   desc: '趣味拼贴，创意满满', img: '', imgActive: '', hidden: true },
 ]
 
-/** 预览图路径约定：/public/aicreate/styles/{styleId}.jpg */
-const previewUrl = (id: string) => `/aicreate/styles/${id}.jpg`
-
-/** 加载失败时切换为对应色调的 SVG 渐变占位 */
-const fallbackSvg = (hue: number) =>
-  'data:image/svg+xml;charset=utf-8,' + encodeURIComponent(
-    `<svg xmlns="http://www.w3.org/2000/svg" width="240" height="240" viewBox="0 0 240 240">` +
-    `<defs><linearGradient id="g" x1="0" y1="0" x2="1" y2="1">` +
-    `<stop offset="0" stop-color="hsl(${hue},65%,84%)"/>` +
-    `<stop offset="1" stop-color="hsl(${(hue + 30) % 360},70%,66%)"/>` +
-    `</linearGradient></defs>` +
-    `<rect width="240" height="240" fill="url(#g)"/>` +
-    `</svg>`
-  )
-
-const onPreviewError = (e: Event, hue: number) => {
-  const img = e.target as HTMLImageElement
-  if (img.dataset.fallback === '1') return // 防止 fallback 也失败导致死循环
-  img.dataset.fallback = '1'
-  img.src = fallbackSvg(hue)
-}
+/** 页面可见的风格列表 */
+const visibleStyles = styles.filter(s => !s.hidden)
 
 const goNext = () => {
   store.selectedStyle = selected.value