fix: address copy functionality and code logic issues for #1828

- utils.jsx: Replace input with textarea in copy function to preserve line breaks in multi-line content, preventing formatting loss mentioned in #1828
- api.js: Fix duplicate 'group' property in buildApiPayload to resolve syntax issues
- MarkdownRenderer.jsx: Refactor code text extraction using textContent for accurate copying

Closes #1828

Signed-off-by: Zhaokun Zhang <zhaokunzhang@Zhaokuns-Air.lan>

web/src/components/common/markdown/MarkdownRenderer.jsx

@@ -181,8 +181,8 @@ export function PreCode(props) {
                 e.preventDefault();
                 e.stopPropagation();
                 if (ref.current) {
-                  const code =
-                    ref.current.querySelector('code')?.innerText ?? '';
+                  const codeElement = ref.current.querySelector('code');
+                  const code = codeElement?.textContent ?? '';
                   copy(code).then((success) => {
                     if (success) {
                       Toast.success(t('代码已复制到剪贴板'));