feat: add Random Generator tool

Cryptographically secure generator for 5 types:
- Password: configurable charset + entropy strength meter
- UUID: crypto.randomUUID()
- API Key: hex/base62/base64url with optional prefix
- Hash: SHA-1/256/512 of custom input or random data
- Token: variable byte-length in hex or base64url

All using Web Crypto API — nothing leaves the browser.
Registered in lib/tools.tsx with RandomIcon (dice).

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

lib/tools.tsx

@@ -1,4 +1,4 @@
-import { ColorIcon, UnitsIcon, ASCIIIcon, MediaIcon, FaviconIcon, QRCodeIcon, AnimateIcon, CalculateIcon } from '@/components/AppIcons';
+import { ColorIcon, UnitsIcon, ASCIIIcon, MediaIcon, FaviconIcon, QRCodeIcon, AnimateIcon, CalculateIcon, RandomIcon } from '@/components/AppIcons';
 
 export interface Tool {
   /** Short display name (e.g. "Color") */
@@ -97,9 +97,20 @@ export const tools: Tool[] = [
     icon: AnimateIcon,
     badges: ['CSS', 'Tailwind v4', '20+ Presets'],
   },
+  {
+    shortTitle: 'Random',
+    title: 'Random Generator',
+    navTitle: 'Random Generator',
+    href: '/random',
+    description: 'Generate cryptographically secure passwords, UUIDs, API keys, hashes and tokens.',
+    summary:
+      'Cryptographically secure random generator. Create passwords, UUIDs, API keys, SHA hashes, and secure tokens — all using the browser Web Crypto API, nothing leaves your machine.',
+    icon: RandomIcon,
+    badges: ['Web Crypto', 'Passwords', 'UUID', 'Hashes'],
+  },
   {
     shortTitle: 'Calculate',
-    title: 'Calculator & Grapher',
+    title: 'Calculator',
     navTitle: 'Calculator',
     href: '/calculate',
     description: 'Advanced expression evaluator with interactive function graphing.',