refactor: Use ActivityService to create system messages in seeder

database/migrations/2026_06_16_225928_create_predefined_mutations_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::create('predefined_mutations', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('dynamic_id')->constrained()->cascadeOnDelete();
+            $table->string('name');
+            $table->text('description')->nullable();
+            $table->integer('amount');
+            $table->string('type')->default('reward');
+            $table->timestamps();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::dropIfExists('predefined_mutations');
+    }
+};

database/migrations/2026_06_16_225946_add_predefined_mutation_id_to_mutations_table.php

@@ -0,0 +1,29 @@
+<?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('mutations', function (Blueprint $table) {
+            $table->foreignId('predefined_mutation_id')->nullable()->constrained()->onDelete('set null');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('mutations', function (Blueprint $table) {
+            $table->dropForeign(['predefined_mutation_id']);
+            $table->dropColumn('predefined_mutation_id');
+        });
+    }
+};