feat: add legacy PDF generation support and invoice discount fields

database/migrations/2026_04_06_152600_add_discount_fields.php

@@ -0,0 +1,38 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::table('invoices', function (Blueprint $table) {
+            if (!Schema::hasColumn('invoices', 'discount_rate')) {
+                $table->integer('discount_rate')->default(0);
+            }
+        });
+
+        Schema::table('invoice_items', function (Blueprint $table) {
+            if (!Schema::hasColumn('invoice_items', 'is_discountable')) {
+                $table->boolean('is_discountable')->default(true);
+            }
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::table('invoices', function (Blueprint $table) {
+            if (Schema::hasColumn('invoices', 'discount_rate')) {
+                $table->dropColumn('discount_rate');
+            }
+        });
+
+        Schema::table('invoice_items', function (Blueprint $table) {
+            if (Schema::hasColumn('invoice_items', 'is_discountable')) {
+                $table->dropColumn('is_discountable');
+            }
+        });
+    }
+};