feat: multi-tenant SaaS implementation - admin interface, tenant isolation, and UI updates

app/Models/Tenant.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Models;
+
+use Illuminate\Database\Eloquent\Model;
+
+use Illuminate\Database\Eloquent\Attributes\Fillable;
+
+#[Fillable(['name'])]
+class Tenant extends Model
+{
+    public function users()
+    {
+        return $this->hasMany(User::class);
+    }
+
+    public function candidates()
+    {
+        return $this->hasMany(Candidate::class);
+    }
+
+    public function quizzes()
+    {
+        return $this->hasMany(Quiz::class);
+    }
+
+    public function jobPositions()
+    {
+        return $this->hasMany(JobPosition::class);
+    }
+}