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/task/migrations/0001_initial.py

@@ -0,0 +1,58 @@
+# Generated by Django 5.1.6 on 2025-03-06 16:03
+
+import django.db.models.deletion
+import django_extensions.db.fields
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='Task',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('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')),
+                ('display', models.IntegerField(unique=True)),
+                ('title', models.CharField(max_length=100)),
+                ('content', models.TextField()),
+                ('task_type', models.CharField(choices=[('challenge', 'Challenge'), ('tutorial', 'Tutorial')], editable=False, max_length=20)),
+                ('is_public', models.BooleanField(default=False)),
+            ],
+            options={
+                'get_latest_by': 'modified',
+                'abstract': False,
+            },
+        ),
+        migrations.CreateModel(
+            name='Challenge',
+            fields=[
+                ('task_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='task.task')),
+                ('score', models.IntegerField(default=0)),
+            ],
+            options={
+                'verbose_name': '挑战',
+                'verbose_name_plural': '挑战',
+                'ordering': ('display',),
+            },
+            bases=('task.task',),
+        ),
+        migrations.CreateModel(
+            name='Tutorial',
+            fields=[
+                ('task_ptr', models.OneToOneField(auto_created=True, on_delete=django.db.models.deletion.CASCADE, parent_link=True, primary_key=True, serialize=False, to='task.task')),
+            ],
+            options={
+                'verbose_name': '教程',
+                'verbose_name_plural': '教程',
+                'ordering': ('display',),
+            },
+            bases=('task.task',),
+        ),
+    ]