feat: implement Learning Tracer (heartbeat duration tracking) for LPK Audit

database/migrations/2026_01_23_115238_add_tracking_columns_to_user_progress_table.php

@@ -0,0 +1,30 @@
+<?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('user_progress', function (Blueprint $table) {
+            $table->timestamp('started_at')->nullable()->after('lesson_id');
+            $table->unsignedInteger('time_spent_seconds')->default(0)->after('completed_at');
+            $table->timestamp('last_heartbeat_at')->nullable()->after('time_spent_seconds');
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('user_progress', function (Blueprint $table) {
+            $table->dropColumn(['started_at', 'time_spent_seconds', 'last_heartbeat_at']);
+        });
+    }
+};