feat: implement adaptive multi-pane mailbox with utilities and security gates

- Added fully responsive 3-pane layout for Mailbox
- Integrated global cinematic Toast system in app shell
- Implemented Copy to Clipboard and QR Code modal utilities
- Added diverse mock email data for premium demonstration
- Implemented security gates for custom mailboxes and attachments
- Fixed critical 500 error for orphaned email selection
- Refined landing page hero CTA text

resources/views/components/bento/nav.blade.php

@@ -29,7 +29,7 @@
         <!-- Right Side: CTA + Mobile Toggle -->
         <div class="flex items-center gap-4 z-50">
             <!-- CTA Button (Desktop & Mobile) -->
-            <a href="#hero" class="relative inline-flex items-center justify-center px-5 py-2.5 text-sm font-semibold text-white bg-zinc-900 border border-zinc-700/80 rounded-full overflow-hidden transition-all group hover:border-pink-500 hover:shadow-[0_0_15px_rgba(236,72,153,0.4)]">
+            <a href="/mailbox" class="relative inline-flex items-center justify-center px-5 py-2.5 text-sm font-semibold text-white bg-zinc-900 border border-zinc-700/80 rounded-full overflow-hidden transition-all group hover:border-pink-500 hover:shadow-[0_0_15px_rgba(236,72,153,0.4)]">
                 <span class="absolute inset-0 w-full h-full transition-all duration-300 ease-out opacity-0 bg-gradient-to-r from-pink-500 to-purple-500 group-hover:opacity-20"></span>
                 <span class="relative flex items-center gap-2 text-zinc-100 group-hover:text-white group-hover:drop-shadow-[0_0_8px_rgba(255,255,255,0.5)]">
                     <span class="hidden sm:inline">Get Temporary Email</span>