feat: complete GSB construction ERP implementation with dual-mode MR, capitalization cap engine, single PM rule, and system sign-off documentation

Modules/ProjectManagement/app/Models/ProjectClassification.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Modules\ProjectManagement\Models;
+
+use Illuminate\Database\Eloquent\Factories\HasFactory;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Database\Eloquent\Relations\BelongsToMany;
+
+class ProjectClassification extends Model
+{
+    use HasFactory;
+
+    protected $fillable = [
+        'name',
+        'code',
+        'description',
+    ];
+
+    public function projects(): BelongsToMany
+    {
+        return $this->belongsToMany(Project::class, 'project_classification_pivot');
+    }
+}