fix: ctrl+enter键不能换行的问题

frontend/src/components/ai-elements/prompt-input.tsx

@@ -883,7 +883,32 @@ export const PromptInputTextarea = ({
       if (!submitOnEnter) {
         return;
       }
+
       if (e.shiftKey || e.ctrlKey || e.metaKey) {
+        // Keep newline behavior explicit for modified-Enter combos.
+        // This avoids accidental submit shortcuts swallowing Ctrl/Cmd+Enter.
+        if (e.ctrlKey || e.metaKey) {
+          e.preventDefault();
+          const target = e.currentTarget;
+          const start = target.selectionStart ?? target.value.length;
+          const end = target.selectionEnd ?? target.value.length;
+          const nextValue =
+            target.value.slice(0, start) + "\n" + target.value.slice(end);
+
+          if (controller) {
+            controller.textInput.setInput(nextValue);
+          } else {
+            target.value = nextValue;
+            const inputEvent = new Event("input", { bubbles: true });
+            target.dispatchEvent(inputEvent);
+          }
+
+          // Place caret right after the inserted newline.
+          requestAnimationFrame(() => {
+            target.selectionStart = start + 1;
+            target.selectionEnd = start + 1;
+          });
+        }
         return;
       }
       e.preventDefault();