feat(题目列表): SQL 题混在一般题里看不出来，点进去才发现不是写 C——和画流程图一样挂「SQL」标签，「全部类型」里也能单独筛

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

apps/api/src/routes/contest.ts

@@ -244,6 +244,7 @@ contestRoutes.get(
             allowFlowchart: problem.allowFlowchart,
             showFlowchart: problem.showFlowchart,
             hasAstRules: problem.astRules !== null,
+            isSql: problem.languages.includes("SQL"),
             myStatus: myStatusOf(statuses, problem.id),
             // 按人数是公开题库列表的列；比赛题表看的是榜单，不下发
             solvedUsers: 0,