新增 SQL 题型：SQLite 内联判题（不依赖外部沙箱）

- SQL 作为语言接入现有提交流程，judge_task 按 language 分流到 SQLJudgeDispatcher
- judge/sql_runner.py：内存 SQLite 判题核心，查询题比结果集/增删改题比表状态，
  authorizer + progress_handler + max_page_count 三重防护
- dispatcher 提取 _process_judge_result/_push_status 供 SQL 判题复用（行为不变）
- 测试点通道支持 1.sql..N.sql 压缩包，出题只需数据脚本+标准答案
- Problem 增加 sql_config 字段；options 数据迁移注册 SQL 语言

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

options/migrations/0002_add_sql_language.py

@@ -0,0 +1,43 @@
+# SysOptions.languages 存在数据库里，_init_option 只在 key 缺失时写入默认值，
+# 因此新增 SQL 语言必须用数据迁移追加到已部署库；不用 reset_languages()（会覆盖管理员的自定义配置）。
+
+from django.db import migrations
+
+SQL_LANGUAGE = {
+    "config": {"template": ""},
+    "name": "SQL",
+    "description": "SQLite 3",
+    "content_type": "text/x-sql",
+}
+
+
+def add_sql_language(apps, schema_editor):
+    SysOptions = apps.get_model("options", "SysOptions")
+    try:
+        option = SysOptions.objects.get(key="languages")
+    except SysOptions.DoesNotExist:
+        # 库还没初始化过 languages，留给 _init_option 用代码默认值（已含 SQL）创建
+        return
+    if not any(item.get("name") == "SQL" for item in option.value):
+        option.value.append(SQL_LANGUAGE)
+        option.save(update_fields=["value"])
+
+
+def remove_sql_language(apps, schema_editor):
+    SysOptions = apps.get_model("options", "SysOptions")
+    try:
+        option = SysOptions.objects.get(key="languages")
+    except SysOptions.DoesNotExist:
+        return
+    option.value = [item for item in option.value if item.get("name") != "SQL"]
+    option.save(update_fields=["value"])
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("options", "0001_initial"),
+    ]
+
+    operations = [
+        migrations.RunPython(add_sql_language, remove_sql_language),
+    ]