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/random/RandomGenerator.tsx

@@ -3,7 +3,7 @@
 import { useState, useCallback } from 'react';
 import { RefreshCw, Copy, Check, Clock } from 'lucide-react';
 import { toast } from 'sonner';
-import { cn } from '@/lib/utils/cn';
+import { cn, actionBtn } from '@/lib/utils';
 import { SliderRow } from '@/components/ui/slider-row';
 import { MobileTabs } from '@/components/ui/mobile-tabs';
 import {
@@ -392,7 +392,7 @@ export function RandomGenerator() {
               <button
                 onClick={() => copy()}
                 disabled={!output}
-                className="flex items-center gap-1.5 px-3 py-2 rounded-lg glass border border-border/30 text-xs font-mono text-muted-foreground hover:text-primary hover:border-primary/30 hover:bg-primary/10 transition-all disabled:opacity-30"
+                className={actionBtn}
               >
                 {copied ? <Check className="w-3.5 h-3.5" /> : <Copy className="w-3.5 h-3.5" />}
                 {copied ? 'Copied' : 'Copy'}