feat: 首页素材画廊增加分类筛选标签

- 后端 SQL 增加 json_extract 提取素材 metaType (frame/spritesheet/preview)
- 前端 AssetGallery 新增分类标签栏：全部/精灵表/帧/场景瓦片/背景/UI
- 按 metaType + assetType 组合过滤展示

backend/internal/handler/generate.go

@@ -313,13 +313,14 @@ type RecentAssetItem struct {
 	Format    string `json:"format"`
 	Prompt    string `json:"prompt"`
 	AssetType string `json:"assetType"`
+	MetaType  string `json:"metaType"` // frame / spritesheet / preview
 	TaskID    string `json:"taskId"`
 	CreatedAt string `json:"createdAt"`
 }
 
 // GetRecentAssets 获取最近生成的素材列表（已完成任务的全部素材）。
 func GetRecentAssets(c *gin.Context) {
-	limit := 20
+	limit := 60
 
 	var dbRows []struct {
 		Key       string
@@ -327,6 +328,7 @@ func GetRecentAssets(c *gin.Context) {
 		Format    string
 		Prompt    string
 		AssetType string
+		MetaType  string
 		TaskID    string
 		ProjectID uint
 		CreatedAt string
@@ -334,6 +336,7 @@ func GetRecentAssets(c *gin.Context) {
 
 	db.GetDB().WithContext(c.Request.Context()).
 		Raw(`SELECT a.key, a.url, a.format, t.prompt, t.asset_type as asset_type,
+			COALESCE(json_extract(a.metadata, '$.type'), 'frame') as meta_type,
 			t.external_id as task_id, t.project_id, t.created_at as created_at
 			FROM assets a
 			INNER JOIN tasks t ON a.task_id = t.id
@@ -350,6 +353,7 @@ func GetRecentAssets(c *gin.Context) {
 			Format:    r.Format,
 			Prompt:    r.Prompt,
 			AssetType: r.AssetType,
+			MetaType:  r.MetaType,
 			TaskID:    r.TaskID,
 			CreatedAt: r.CreatedAt,
 		}

frontend/src/api/types.ts

@@ -105,6 +105,7 @@ export interface RecentAssetItem {
   format: string
   prompt: string
   assetType: string
+  metaType: string
   taskId: string
   createdAt: string
 }

frontend/src/components/AssetGallery.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState } from 'react'
+import { useEffect, useState, useMemo } from 'react'
 import { getRecentAssets } from '../api/generate'
 import type { RecentAssetItem } from '../api/types'
 
@@ -9,9 +9,38 @@ const ASSET_TYPE_LABELS: Record<string, string> = {
   animation: '动画',
 }
 
+const CATEGORIES = [
+  { key: 'all', label: '全部' },
+  { key: 'spritesheet', label: '精灵表' },
+  { key: 'frame', label: '帧' },
+  { key: 'tileset', label: '场景瓦片' },
+  { key: 'background', label: '背景' },
+  { key: 'ui', label: 'UI' },
+]
+
+function matchCategory(item: RecentAssetItem, cat: string): boolean {
+  switch (cat) {
+    case 'all':
+      return true
+    case 'spritesheet':
+      return item.metaType === 'spritesheet'
+    case 'frame':
+      return item.metaType === 'frame' || item.metaType === 'preview' || item.format === 'gif'
+    case 'tileset':
+      return item.assetType === 'sprite' && item.metaType === 'spritesheet'
+    case 'background':
+      return item.assetType === 'background'
+    case 'ui':
+      return item.assetType === 'ui'
+    default:
+      return true
+  }
+}
+
 export default function AssetGallery() {
   const [assets, setAssets] = useState<RecentAssetItem[]>([])
   const [loading, setLoading] = useState(true)
+  const [activeCat, setActiveCat] = useState('all')
 
   useEffect(() => {
     getRecentAssets()
@@ -20,13 +49,45 @@ export default function AssetGallery() {
       .finally(() => setLoading(false))
   }, [])
 
-  if (loading) return null
+  const filtered = useMemo(
+    () => assets.filter(item => matchCategory(item, activeCat)),
+    [assets, activeCat]
+  )
 
+  if (loading) return null
   if (assets.length === 0) return null
 
   return (
     <section style={{ marginBottom: 32 }}>
-      <h2 style={{ fontSize: 18, marginBottom: 16 }}>最近生成</h2>
+      <h2 style={{ fontSize: 18, marginBottom: 12 }}>最近生成</h2>
+
+      {/* 分类标签 */}
+      <div style={{ display: 'flex', gap: 8, marginBottom: 16, flexWrap: 'wrap' }}>
+        {CATEGORIES.map(cat => (
+          <button
+            key={cat.key}
+            type="button"
+            onClick={() => setActiveCat(cat.key)}
+            style={{
+              fontSize: 13,
+              padding: '4px 14px',
+              borderRadius: 999,
+              border: `1px solid ${activeCat === cat.key ? 'var(--accent)' : 'var(--border)'}`,
+              background: activeCat === cat.key ? 'var(--accent-dim)' : 'transparent',
+              color: activeCat === cat.key ? 'var(--accent)' : 'var(--text-secondary)',
+              cursor: 'pointer',
+              fontWeight: activeCat === cat.key ? 600 : 400,
+            }}
+          >
+            {cat.label}
+          </button>
+        ))}
+      </div>
+
+      {/* 素材网格 */}
+      {filtered.length === 0 ? (
+        <p style={{ fontSize: 13, color: 'var(--text-muted)' }}>暂无此类素材</p>
+      ) : (
         <div
           style={{
             display: 'grid',
@@ -34,15 +95,11 @@ export default function AssetGallery() {
             gap: 12,
           }}
         >
-        {assets.map((item, i) => (
+          {filtered.map((item, i) => (
             <div
               key={`${item.taskId}-${i}`}
               className="card"
-            style={{ padding: 8, cursor: 'pointer' }}
-            onClick={() => {
-              // navigate to result page — need projectId for URL
-              // For now just open the image
-            }}
+              style={{ padding: 8 }}
             >
               <div
                 style={{
@@ -95,6 +152,7 @@ export default function AssetGallery() {
             </div>
           ))}
         </div>
+      )}
     </section>
   )
 }