chore: 将后端移动到 api/ 目录，准备合并为单仓库

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/submission/migrations/0001_initial.py

@@ -0,0 +1,38 @@
+# Generated by Django 5.1.6 on 2025-03-18 11:36
+
+import django.db.models.deletion
+import django_extensions.db.fields
+import uuid
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ('task', '0004_alter_task_task_type'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Submission',
+            fields=[
+                ('created', django_extensions.db.fields.CreationDateTimeField(auto_now_add=True, verbose_name='created')),
+                ('modified', django_extensions.db.fields.ModificationDateTimeField(auto_now=True, verbose_name='modified')),
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('score', models.IntegerField(default=0, verbose_name='分数')),
+                ('html', models.TextField(blank=True, null=True, verbose_name='HTML代码')),
+                ('css', models.TextField(blank=True, null=True, verbose_name='CSS代码')),
+                ('js', models.TextField(blank=True, null=True, verbose_name='JS代码')),
+                ('referee', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='referee_submissions', to=settings.AUTH_USER_MODEL, verbose_name='打分人')),
+                ('task', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to='task.task')),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='my_submissions', to=settings.AUTH_USER_MODEL)),
+            ],
+            options={
+                'ordering': ('-created',),
+            },
+        ),
+    ]