feat(ui): 调整聊天页布局比例及 artifacts 滚动条遮挡处理

- 修改 artifactsOpen 时容器宽度从 70% 改为 50%
- 文件阅读区添加圆角样式
- 文件阅读区添加滚动条顶部遮挡层，优化视觉体验
- 代码编辑器增加 py-[20px] 内边距
- InputBox 已提交状态强制显示阴影效果

frontend/src/app/workspace/chats/[thread_id]/page.tsx

@@ -255,7 +255,7 @@ export default function ChatPage() {
       <div
         className={cn(
           "m-auto flex h-screen min-h-svh overflow-hidden rounded-t-[20px] transition-[width] duration-300 ease-in-out",
-          artifactsOpen ? "w-full" : "w-[70%]",
+          artifactsOpen ? "w-full" : "w-[50%]",
         )}
       >
         <div className="relative flex size-full min-h-0 justify-between rounded-t-[20px]">
@@ -372,7 +372,7 @@ export default function ChatPage() {
               artifactPanelOpen
                 ? fullscreen
                   ? "ml-0 w-full"
-                  : "w-[70%]"
+                  : "w-[50%]"
                 : "w-0",
             )}
           >

frontend/src/components/ai-elements/artifact.tsx

@@ -140,7 +140,7 @@ export const ArtifactContent = ({
   className,
   ...props
 }: ArtifactContentProps) => (
-  <div className="min-h-0 flex-1 overflow-auto">
+  <div className="min-h-0 rounded-[10px] flex-1 overflow-auto">
     <div className={cn("mb-[150px] p-4", className)} {...props} />
   </div>
 );

frontend/src/components/workspace/artifacts/artifact-file-detail.tsx

@@ -154,7 +154,8 @@ export function ArtifactFileDetail({
     }
   }, [threadId, filepath, isInstalling]);
   return (
-    <Artifact className={cn(className)}>
+    // 给滚动遮挡头部定位relative
+    <Artifact className={cn("relative",className)}>
       <ArtifactHeader>
         <div className="flex items-center justify-start gap-2">
           {previewable && (
@@ -387,7 +388,9 @@ export function ArtifactFileDetail({
           </ArtifactActions>
         </div>
       </ArtifactHeader>
-      <ArtifactContent className="rounded-[10px] bg-white p-0">
+      <ArtifactContent className=" rounded-b-[10px] bg-white p-0">
+        {/* 遮挡多余的滚动顶部 */}
+        <div className="absolute w-[calc(100%-40px)] bg-white z-20 h-5 rounded-t-[10px] top-[57px]"></div>
         {previewable &&
           viewMode === "preview" &&
           (language === "markdown" || language === "html") && (
@@ -399,7 +402,7 @@ export function ArtifactFileDetail({
           )}
         {isCodeFile && viewMode === "code" && (
           <CodeEditor
-            className="size-full resize-none rounded-none border-none"
+            className="size-full py-[20px] resize-none rounded-none border-none"
             value={displayContent ?? ""}
             zoom={zoom}
             readonly

frontend/src/components/workspace/input-box.tsx

@@ -307,6 +307,7 @@ export function InputBox({
           "border-0 rounded-[20px] backdrop-blur-sm",
           "transition-[height] duration-300 ease-out shadow-none ",
           !isNewThread && "h-[200px] shadow-[0_0_20px_0_rgba(0,0,0,0.10)]",
+          hasSubmitted&& "shadow-[0_0_20px_0_rgba(0,0,0,0.10)]!",
           effectiveIsFocused ? "h-[200px]" : "h-[80px]",
         )}
         disabled={disabled}