新增 SQL 题型前端支持

- LANGUAGE 类型与六张语言映射表补 SQL；编辑器 SQLite 方言高亮
- 出题表单：SQL 语言选项、题型/行序配置卡片、数据脚本压缩包上传、标准答案必填校验
- 修复做题页语言回退硬编码 Python3 的问题（SQL 题会提交被拒）
- SQL 题隐藏自测猫/自测屏/复制到自测猫（外部运行器不支持 SQL）

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

src/shared/components/SyncCodeEditor.vue

@@ -1,6 +1,7 @@
 <script lang="ts" setup>
 import { cpp } from "@codemirror/lang-cpp"
 import { python } from "@codemirror/lang-python"
+import { sql, SQLite } from "@codemirror/lang-sql"
 import { bracketMatching } from "@codemirror/language"
 import { EditorView } from "@codemirror/view"
 import { Codemirror } from "vue-codemirror"
@@ -57,6 +58,8 @@ const emit = defineEmits<{
 const { isDesktop } = useBreakpoints()
 
 const langExtension = computed((): Extension => {
+  if (language === "SQL")
+    return sql({ dialect: SQLite, upperCaseKeywords: true })
   return ["Python2", "Python3"].includes(language) ? python() : cpp()
 })
 

src/shared/extensions/autocompletion.ts

@@ -27,6 +27,9 @@ export function enhanceCompletion(language: LANGUAGE): CompletionSource {
     const word = context.matchBefore(/\w+/)
     if (!word && !context.explicit) return null
 
+    // SQL 没有中文注释提示，关键字补全由 @codemirror/lang-sql 提供
+    if (language === "SQL") return null
+
     const trulyLanguage = language.startsWith("Python") ? "python" : "c"
     const completions: Completion[] = (
       chineseAnnotations[trulyLanguage] || []