feat: Phase 2 - Laravel Reverb + real-time notifications

- Install laravel/reverb + laravel-echo + pusher-js
- Configure broadcasting to reverb in .env.example + .env
- Add Echo + Pusher client in resources/js/app.js
- Update all 14 notifications to implement ShouldBroadcast + broadcastOn()
- Update NotificationBell component to listen for real-time events
- Add Livewire.emit in notification-bell blade for JS-to-Livewire bridge

Tests: 101 passing (319 assertions)

composer.json

@@ -10,6 +10,7 @@
         "blade-ui-kit/blade-heroicons": "^2.7",
         "gasparesganga/php-shapefile": "^3.4",
         "laravel/framework": "^12.0",
+        "laravel/reverb": "^1.11",
         "laravel/sanctum": "^4.3",
         "laravel/tinker": "^2.10.1",
         "league/geotools": "^1.3",