- WhatsAppService now reads credentials from messaging_channels table
  (encrypted:array cast) instead of config/env vars
- New MessagingSettings Livewire page to configure credentials from UI
- Webhook verify token also read from DB
- API Keys page auto-pushes MESSAGING_HUB_URL + KEY to instances
  via CapRover env vars on generate/regenerate
- Sidebar shows messaging sub-nav when on messaging pages
- Removed hardcoded whatsapp config from manager.php
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>