Implement parent child ticket hierarchy

database/migrations/2026_03_25_072501_add_parent_ticket_id_to_tickets_table.php

@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('tickets', function (Blueprint $table) {
+            $table->foreignId('parent_ticket_id')
+                ->nullable()
+                ->after('board_column_id')
+                ->constrained('tickets')
+                ->nullOnDelete();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('tickets', function (Blueprint $table) {
+            $table->dropConstrainedForeignId('parent_ticket_id');
+        });
+    }
+};