feat: add SQL index on device_id and update_time for t_user_calendar_categories

New_eCalendar/26_前端解析RRULE/26_前端解析RRULE.sql

-# MongoDB 索引
+# MongoDB 索引
@@ -2,4 +2,9 @@
 db.events.createIndex(
     { "deviceId": 1, "updatedAt": -1 },
     { name: "idx_deviceId_updatedAt", background: true }
-)
\ No newline at end of file
+)
+
+# SQL 索引
+create index idx_device_id_update_time
+    on t_user_calendar_categories (device_id, update_time);
+