add heatmap

submission/migrations/0002_submission_user_create_time_idx.py

@@ -0,0 +1,19 @@
+# Generated by Django 5.2.3 on 2025-09-25 07:03
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('contest', '0001_initial'),
+        ('problem', '0001_initial'),
+        ('submission', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name='submission',
+            index=models.Index(fields=['user_id', 'create_time'], name='user_create_time_idx'),
+        ),
+    ]