fix: align highlight layer with textarea to fix misalignment issue

- Match padding values between highlight layer and textarea
- Use same padding logic for edit mode (pt-1.5 pb-10 px-2) and normal mode (py-1.5 px-2)
- Add pr-9 to highlight layer to match textarea right padding
- Fixes #6647

webview-ui/src/components/chat/ChatTextArea.tsx

@@ -1011,8 +1011,8 @@ const ChatTextArea = forwardRef<HTMLTextAreaElement, ChatTextAreaProps>(
 						"font-vscode-font-family",
 						"text-vscode-editor-font-size",
 						"leading-vscode-editor-line-height",
-						"py-2",
-						"px-[9px]",
+						isEditMode ? "pt-1.5 pb-10 px-2" : "py-1.5 px-2",
+						"pr-9",
 						"z-10",
 						"forced-color-adjust-none",
 					)}