refactor: centralize action/icon button styles across all tools

Extract shared actionBtn and iconBtn constants into lib/utils/styles.ts
and replace all 11 local definitions across tool components.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

components/ascii/FontPreview.tsx

@@ -13,7 +13,7 @@ import {
   MessageSquareCode,
   Type,
 } from 'lucide-react';
-import { cn } from '@/lib/utils/cn';
+import { cn, actionBtn } from '@/lib/utils';
 import { toast } from 'sonner';
 
 export type CommentStyle = 'none' | '//' | '#' | '--' | ';' | '/* */' | '<!-- -->' | '"""';
@@ -116,9 +116,6 @@ export function FontPreview({
     }
   };
 
-  const actionBtn =
-    'flex items-center gap-1 px-2.5 py-1 text-xs glass rounded-md border border-border/30 text-muted-foreground hover:text-primary hover:border-primary/30 hover:bg-primary/10 transition-all';
-
   return (
     <div className={cn('glass rounded-xl p-4 flex flex-col gap-3 flex-1 min-h-0 overflow-hidden', className)}>