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)

app/Notifications/TaskCommentNotification.php

@@ -5,9 +5,10 @@ namespace App\Notifications;
 use App\Models\Comment;
 use App\Models\Task;
 use Illuminate\Bus\Queueable;
+use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
 use Illuminate\Notifications\Notification;
 
-class TaskCommentNotification extends Notification
+class TaskCommentNotification extends Notification implements ShouldBroadcast
 {
     use Queueable;
 
@@ -15,7 +16,7 @@ class TaskCommentNotification extends Notification
 
     public function via($notifiable): array
     {
-        return ['database'];
+        return ['database', 'broadcast'];
     }
 
     public function toArray($notifiable): array
@@ -28,4 +29,12 @@ class TaskCommentNotification extends Notification
             'message' => "Nuevo comentario en '{$this->task->title}' por {$this->comment->user->name}: ".substr($this->comment->body, 0, 100),
         ];
     }
-}
+
+    public function broadcastOn(): array
+    {
+        $userIds = [];
+        if ($this->task->assigned_to) $userIds[] = $this->task->assigned_to;
+        if ($this->task->created_by) $userIds[] = $this->task->created_by;
+        return array_map(fn ($id) => new \Illuminate\Broadcasting\PrivateChannel("user.{$id}"), array_unique($userIds));
+    }
+}