chore: update document approval workflow and bug fixes

Modules/ApprovalWorkflow/app/Models/ApprovalStep.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Modules\ApprovalWorkflow\Models;
+
+use App\Models\User;
+use App\Traits\HasPublicIdentifier;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsTo;
+use Modules\ApprovalWorkflow\Enums\ApprovalStepStatus;
+
+class ApprovalStep extends Model
+{
+    use HasPublicIdentifier;
+
+    protected $fillable = [
+        'approval_chain_id',
+        'approver_id',
+        'order',
+        'status',
+        'notes',
+        'acted_at',
+    ];
+
+    protected function casts(): array
+    {
+        return [
+            'status' => ApprovalStepStatus::class,
+            'acted_at' => 'datetime',
+        ];
+    }
+
+    public function chain(): BelongsTo
+    {
+        return $this->belongsTo(ApprovalChain::class, 'approval_chain_id');
+    }
+
+    public function approver(): BelongsTo
+    {
+        return $this->belongsTo(User::class, 'approver_id');
+    }
+
+    public function isPending(): bool
+    {
+        return $this->status === ApprovalStepStatus::Pending;
+    }
+}