phsl / new-api

- 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>