feat: add global server custom CSS (#6753)

* feat: add global server custom CSS

* refactor: reuse CodeMirror for CSS editors

apps/nextjs/src/components/custom-css/custom-css-editor.tsx

@@ -0,0 +1,38 @@
+"use client";
+
+import { CodeEditor } from "~/components/custom-widgets/code-editor";
+
+interface CustomCssEditorProps {
+  id: string;
+  label: string;
+  description: string;
+  value?: string;
+  onChange: (value: string) => void;
+  error?: React.ReactNode;
+  actions?: React.ReactNode;
+}
+
+export const CustomCssEditor = ({
+  id,
+  label,
+  description,
+  value = "",
+  onChange,
+  error,
+  actions,
+}: CustomCssEditorProps) => {
+  return (
+    <CodeEditor
+      id={id}
+      label={label}
+      description={description}
+      value={value}
+      onChange={onChange}
+      error={error}
+      language="css"
+      height="250px"
+      maxLength={16_384}
+      actions={actions}
+    />
+  );
+};