feat(ui): 对话输入框 Enter 换行,Ctrl/Cmd+Enter 发送

会话界面共享 Composer 与任务详情主 Agent 输入框统一改为回车换行,避免长消息
误发。任务详情原本是单行 Input(根本无法换行),换成 Textarea 并对齐 Composer
的自动增高样式(rows=1 + max-h-40)。

web/src/app/(main)/chat/page.tsx

@@ -77,8 +77,8 @@ function LiveBadge() {
   );
 }
 
-// Composer is the shared bottom input (textarea grows to a cap, Enter sends,
-// Shift+Enter newlines) — the same affordance across DraftChat and ChatView.
+// Composer is the shared bottom input (textarea grows to a cap, Enter newlines,
+// Ctrl/Cmd+Enter sends) — the same affordance across DraftChat and ChatView.
 function Composer({
   value,
   onChange,
@@ -112,7 +112,8 @@ function Composer({
   const fileInputRef = React.useRef<HTMLInputElement>(null);
   const atts = attachments ?? [];
   function onKeyDown(e: React.KeyboardEvent<HTMLTextAreaElement>) {
-    if (e.key === "Enter" && !e.shiftKey) {
+    // Enter 换行；只有 Ctrl/Cmd+Enter 才发送(避免长消息误发)。
+    if (e.key === "Enter" && (e.ctrlKey || e.metaKey)) {
       e.preventDefault();
       onSend();
     }
@@ -363,7 +364,7 @@ function DraftChat({
         onChange={setInput}
         onSend={send}
         disabled={sending || uploading || !agentKey}
-        placeholder="输入消息，Enter 发送，Shift+Enter 换行"
+        placeholder="输入消息，Enter 换行，Ctrl+Enter 发送"
         leftSlot={agentPicker}
         onPickFiles={pickFiles}
         uploading={uploading}
@@ -691,7 +692,7 @@ function ChatView({
         onChange={setInput}
         onSend={send}
         disabled={running}
-        placeholder={running ? "Agent 正在回复…" : "输入消息，Enter 发送，Shift+Enter 换行"}
+        placeholder={running ? "Agent 正在回复…" : "输入消息，Enter 换行，Ctrl+Enter 发送"}
         running={running}
         onStop={stop}
         stopDisabled={stopping}

web/src/app/(main)/function/tasks/detail/_tabs/sessions-tab.tsx

@@ -24,7 +24,7 @@ import { cn } from "@/lib/utils";
 import { Transcript } from "@/components/transcript";
 import { TodoPopover } from "@/components/todo-popover";
 import { Button } from "@/components/ui/button";
-import { Input } from "@/components/ui/input";
+import { Textarea } from "@/components/ui/textarea";
 import { ScrollArea } from "@/components/ui/scroll-area";
 import {
   Tooltip,
@@ -1070,7 +1070,7 @@ export function SessionsTab({ taskId }: { taskId: string }) {
                 ))}
               </div>
             )}
-            <div className="flex items-center gap-2">
+            <div className="flex items-end gap-2">
               <input
                 ref={fileInputRef}
                 type="file"
@@ -1087,12 +1087,18 @@ export function SessionsTab({ taskId }: { taskId: string }) {
               >
                 {uploading ? <Loader2Icon className="animate-spin" /> : <PaperclipIcon />}
               </Button>
-              <Input
-                placeholder="给主 Agent 发消息，引导探索方向…"
+              <Textarea
+                className="max-h-40 min-h-9 flex-1 resize-none"
+                rows={1}
+                placeholder="给主 Agent 发消息，Enter 换行，Ctrl+Enter 发送…"
                 value={input}
                 onChange={(e) => setInput(e.target.value)}
                 onKeyDown={(e) => {
-                  if (e.key === "Enter" && !mainLive) send();
+                  // Enter 换行；只有 Ctrl/Cmd+Enter 才发送。
+                  if (e.key === "Enter" && (e.ctrlKey || e.metaKey)) {
+                    e.preventDefault();
+                    if (!mainLive) send();
+                  }
                 }}
                 disabled={mainLive}
               />