feat(ui): complete drainage workbench style migration

src/shared/ai-elements/code-block.tsx

@@ -1,5 +1,3 @@
-"use client";
-
 import { Button } from "@/shared/ui/button";
 import {
   Select,
@@ -8,7 +6,7 @@ import {
   SelectTrigger,
   SelectValue,
 } from "@/shared/ui/select";
-import { cn } from "@/lib/utils";
+import { cn } from "@/shared/ui/cn";
 import { CheckIcon, CopyIcon } from "lucide-react";
 import type { ComponentProps, CSSProperties, HTMLAttributes } from "react";
 import {