style: 画布编辑器多行输入框样式调整 (#130)

复用了画布agent的输入框:

* 高度自适应
* 滑动条样式变为浅色和位置不再出界

before
![shotmd-1785745933-compressed.webp](/attachments/95727f6d-63e1-48f7-b806-8203cd73d1eb)
after
![shotmd-1785745957-compressed.webp](/attachments/b5af077d-d3b9-4572-9135-39e288291e24)

Reviewed-on: http://192.168.35.82/git/GenarrativeAI/Genarrative/pulls/130
Co-authored-by: 王德宇 <kvtodev@outlook.com>
Co-committed-by: 王德宇 <kvtodev@outlook.com>

src/index.css

@@ -8725,7 +8725,7 @@ button.image-canvas-editor__reference-chip:disabled {
 
 .image-canvas-editor__generate-prompt {
   min-height: 7rem;
-  resize: vertical;
+  resize: none;
   border: 1px solid #d9dee8;
   border-radius: 0.45rem;
   background: #f8fafc;
@@ -16728,28 +16728,28 @@ button {
   background: #3f3f46;
 }
 
-.editor-agent-conversation__draft-input {
+.auto-grow-text-area {
   scrollbar-color: #cbd5e1 transparent;
   scrollbar-width: thin;
 }
 
-.editor-agent-conversation__draft-input::-webkit-scrollbar {
+.auto-grow-text-area::-webkit-scrollbar {
   width: 6px;
 }
 
-.editor-agent-conversation__draft-input::-webkit-scrollbar-track {
+.auto-grow-text-area::-webkit-scrollbar-track {
   margin-block: 10px;
   background-color: transparent;
 }
 
-.editor-agent-conversation__draft-input::-webkit-scrollbar-thumb {
+.auto-grow-text-area::-webkit-scrollbar-thumb {
   border: 1px solid transparent;
   border-radius: 999px;
   background-color: #cbd5e1;
   background-clip: padding-box;
 }
 
-.editor-agent-conversation__draft-input::-webkit-scrollbar-thumb:hover {
+.auto-grow-text-area::-webkit-scrollbar-thumb:hover {
   background-color: #94a3b8;
 }