feat: 多页面拖拽上传、滚动条精简、UI优化

- 剧本评测/分辨率提升/数字人/角色迁移/图片工作台/去水印/电商：新增外部拖拽文件上传
- 电商：爆款图复刻上传框支持拖拽+大滚动条，短视频/模特图/详情图滚动条精简回退
- 图片工作台：右侧输出面板移至左侧提示词上方，删除局部重绘遮罩/结果框
- 数字人：生成按钮改为「开始生成」
- 局部重绘：编辑遮罩→编辑页面
- 对话框生成器：新增对话/视频模式、模型/速度/深度选择按钮
- 视频时长默认改为5秒
- 工具箱页面空状态logo统一绿底亮色图标
- 多处CSS滚动条和布局优化

src/features/subtitle-removal/SubtitleRemovalPage.tsx

@@ -12,7 +12,7 @@ import {
   SwapOutlined,
   VideoCameraOutlined,
 } from "@ant-design/icons";
-import { useCallback, useEffect, useRef, useState, type CSSProperties } from "react";
+import { useCallback, useEffect, useRef, useState, type CSSProperties, type DragEvent } from "react";
 import { aiGenerationClient } from "../../api/aiGenerationClient";
 import { waitForTask } from "../../api/taskSubscription";
 import { saveToolTaskState, loadToolTaskState, clearToolTaskState } from "../workbench/toolKeepalive";
@@ -73,6 +73,7 @@ function SubtitleRemovalPage({
   const [isProcessing, setIsProcessing] = useState(false);
   const [isDownloading, setIsDownloading] = useState(false);
   const [isSavingAsset, setIsSavingAsset] = useState(false);
+  const [isDragging, setIsDragging] = useState(false);
   const activeTaskIdRef = useRef(activeTaskId);
   activeTaskIdRef.current = activeTaskId;
   const keepaliveRestoredRef = useRef(false);
@@ -125,10 +126,7 @@ function SubtitleRemovalPage({
     event.currentTarget.value = "";
   };
 
-  const handleFileDrop = (event: React.DragEvent) => {
-    event.preventDefault();
-    const file = Array.from(event.dataTransfer.files).find((f) => f.type.startsWith("video/"));
-    if (!file) return;
+  const processDroppedFile = (file: File) => {
     if (sourcePreview.startsWith("blob:")) URL.revokeObjectURL(sourcePreview);
     setSourceName(file.name);
     setSourceFile(file);
@@ -140,6 +138,10 @@ function SubtitleRemovalPage({
     setStatus(`已导入 ${file.name}`);
   };
 
+  const handleDragOver = (e: DragEvent<HTMLDivElement>) => { e.preventDefault(); e.stopPropagation(); if (e.dataTransfer.types.includes("Files")) setIsDragging(true); };
+  const handleDragLeave = (e: DragEvent<HTMLDivElement>) => { e.preventDefault(); e.stopPropagation(); if (e.currentTarget === e.target || !e.currentTarget.contains(e.relatedTarget as Node)) setIsDragging(false); };
+  const handleFileDrop = (e: DragEvent<HTMLDivElement>) => { e.preventDefault(); e.stopPropagation(); setIsDragging(false); const file = Array.from(e.dataTransfer.files).find((f) => f.type.startsWith("video/")); if (file) processDroppedFile(file); };
+
   const handleImportUrl = () => {
     const normalized = sourceUrl.trim();
     if (!/^https?:\/\//i.test(normalized)) {
@@ -341,7 +343,13 @@ function SubtitleRemovalPage({
               accept="video/mp4"
               onChange={handleFileChange}
             />
-            <div className="image-workbench-upload-shell" onDragOver={(e) => e.preventDefault()} onDrop={handleFileDrop}>
+            <div
+              className={`image-workbench-upload-shell${isDragging ? " is-dragging" : ""}`}
+              onDragOver={handleDragOver}
+              onDragLeave={handleDragLeave}
+              onDrop={handleFileDrop}
+            >
+              {isDragging ? <div className="image-workbench-upload-drop-overlay"><span>释放文件以上传</span></div> : null}
               <button type="button" className="image-workbench-upload" onClick={() => fileInputRef.current?.click()}>
                 <FileImageOutlined />
                 <strong>{sourceName || "拖拽或选择视频"}</strong>
@@ -435,9 +443,17 @@ function SubtitleRemovalPage({
               )}
             </div>
           ) : (
-            <div className="image-workbench-empty-canvas">
-              <DeleteOutlined style={{ fontSize: 48, opacity: 0.2 }} />
-              <p>上传视频后在此预览</p>
+            <div
+              className="studio-canvas-ghost"
+              onDragOver={handleDragOver}
+              onDragLeave={handleDragLeave}
+              onDrop={handleFileDrop}
+            >
+              <div className="studio-canvas-ghost__icon">
+                <VideoCameraOutlined />
+              </div>
+              <div className="studio-canvas-ghost__title">拖拽或选择视频</div>
+              <div className="studio-canvas-ghost__hint">仅支持 MP4，最大 1GB，最高 1080P</div>
             </div>
           )}
         </section>