feat: 新增引导式新手指引 (OnboardingTour) 组件，全站页面接入

src/features/image-workbench/ImageWorkbenchPage.tsx

@@ -947,19 +947,22 @@ function ImageWorkbenchPage({ initialTool = "workbench", onOpenMore, onSelectVie
                 </div>
               </div>
             ) : (
-              <button
-                type="button"
-                className={`image-workbench-empty image-workbench-empty--button${isInpaintDragging ? " is-dragging" : ""}`}
+              <div
+                className={`studio-canvas-ghost${isInpaintDragging ? " is-dragging" : ""}`}
                 onClick={() => inpaintFileInputRef.current?.click()}
                 onDragOver={handleInpaintDragOver}
                 onDragLeave={handleInpaintDragLeave}
                 onDrop={handleInpaintDrop}
+                role="button"
+                tabIndex={0}
+                onKeyDown={(e) => { if (e.key === "Enter" || e.key === " ") inpaintFileInputRef.current?.click(); }}
               >
-                {isInpaintDragging ? <span className="image-workbench-upload-drop-overlay" style={{ borderRadius: "var(--radius-sm)" }}><span>释放文件以上传</span></span> : null}
-                <FileImageOutlined />
-                <strong>拖拽或选择图片</strong>
-                <span>支持 PNG / JPG / WebP</span>
-              </button>
+                <div className="studio-canvas-ghost__icon">
+                  <FileImageOutlined />
+                </div>
+                <div className="studio-canvas-ghost__title">点击或拖拽上传图片</div>
+                <div className="studio-canvas-ghost__hint">支持 PNG / JPG / WebP，上传后使用画笔标注需要重绘的区域</div>
+              </div>
             )}
           </section>
 
@@ -1389,12 +1392,21 @@ function ImageWorkbenchPage({ initialTool = "workbench", onOpenMore, onSelectVie
               <img src={referenceImage} alt="参考图预览" />
             </div>
           ) : (
-            <div className="studio-canvas-ghost">
+            <div
+              className={`studio-canvas-ghost${isDragging ? " is-dragging" : ""}`}
+              onClick={() => fileInputRef.current?.click()}
+              onDragOver={handleDragOver}
+              onDragLeave={handleDragLeave}
+              onDrop={handleDrop}
+              role="button"
+              tabIndex={0}
+              onKeyDown={(e) => { if (e.key === "Enter" || e.key === " ") fileInputRef.current?.click(); }}
+            >
               <div className="studio-canvas-ghost__icon">
                 <PictureOutlined />
               </div>
               <div className="studio-canvas-ghost__title">上传参考图后在此预览</div>
-              <div className="studio-canvas-ghost__hint">生成结果也会显示在这里</div>
+              <div className="studio-canvas-ghost__hint">点击或拖拽上传 (PNG / JPG / WebP)，生成结果也会显示在这里</div>
             </div>
           )}
         </section>