fix: implementasi FilamentUser interface agar panel bisa diakses di production

- Tambah FilamentUser interface di User model
- Tambah canAccessPanel() method
- Tambah VoteObserver: broadcast notifikasi ke semua user saat vote baru
- Tambah NotificationService::toAll()
- Fix Vote model: auto-fill created_by via booted()
- Fix CashRecordObserver: fallback created_by untuk Vote

app/Models/Vote.php

@@ -17,6 +17,13 @@ class Vote extends Model
         'deadline' => 'datetime',
     ];
 
+    protected static function booted(): void
+    {
+        static::creating(function (Vote $vote) {
+            $vote->created_by ??= auth()->id();
+        });
+    }
+
     public function creator(): BelongsTo
     {
         return $this->belongsTo(User::class, 'created_by');