feat: 视频素材缩略图改为可播放video预览

- 视频素材(isVideo+file_url)使用video标签自动循环播放
- 无file_url时fallback到thumbnail_url静态图
- 非视频素材保持原有img/fallback逻辑

apps/web/src/pages/generate/components/material/ManualMaterialList.tsx

@@ -34,7 +34,6 @@ const ManualMaterialList: React.FC<ManualMaterialListProps> = ({
             const checked = selectedMaterials.includes(m.id)
             const isVideo = m.mime_type?.startsWith("video/") ?? false
             // thumbnail_url 是静态截图，可直接用于 <img>
-            // file_url 是视频/音频文件本身，<img> 无法渲染，不能作为 src 回退
             const thumbSrc = m.thumbnail_url || undefined
             return (
               <label
@@ -73,7 +72,20 @@ const ManualMaterialList: React.FC<ManualMaterialListProps> = ({
                     justifyContent: "center",
                   }}
                 >
-                  {thumbSrc ? (
+                  {isVideo && m.file_url ? (
+                    <video
+                      src={m.file_url}
+                      muted
+                      loop
+                      playsInline
+                      autoPlay
+                      style={{
+                        width: "100%",
+                        height: "100%",
+                        objectFit: "cover",
+                      }}
+                    />
+                  ) : thumbSrc ? (
                     <img
                       src={thumbSrc}
                       alt={m.name}
@@ -90,13 +102,14 @@ const ManualMaterialList: React.FC<ManualMaterialListProps> = ({
                       }}
                     />
                   ) : null}
-                  {!thumbSrc && (
-                    <span style={{ fontSize: 20, opacity: 0.5, display: "flex" }}>
-                      {isVideo ? "🎬" : "🎵"}
-                    </span>
+                  {!thumbSrc && !isVideo && (
+                    <span style={{ fontSize: 20, opacity: 0.5, display: "flex" }}>🎵</span>
+                  )}
+                  {!thumbSrc && isVideo && !m.file_url && (
+                    <span style={{ fontSize: 20, opacity: 0.5, display: "flex" }}>🎬</span>
                   )}
                   {/* img onError 时显示的 fallback（初始隐藏） */}
-                  {thumbSrc && (
+                  {thumbSrc && !(isVideo && m.file_url) && (
                     <span style={{ fontSize: 20, opacity: 0.5, display: "none" }}>
                       {isVideo ? "🎬" : "🎵"}
                     </span>