fix(班级筛选): 输入 ks251 会把 2511 班的学生也算进来

班级号 3~4 位并存，按用户名前缀/包含匹配时 ks251 会捞到 ks2510~ks2519。
新增 classPrefixCondition：ks + 3 位以上数字按具体班级匹配（后面不能再跟数字），
1~2 位仍是年级前缀。后台首页的用户排名、随机抽签，以及题单的学生进度筛选
（只填数字时补上 ks）都改用它。

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

apps/api/src/routes/admin/account.ts

@@ -34,7 +34,7 @@ import { revokeUserSessions } from "../../auth/session"
 import { requireSuperAdmin, type AppEnv } from "../../auth/middleware"
 import { db, schema } from "../../db"
 import { failure, parseBody, success } from "../../http"
-import { queryInteger, sampleUser } from "../helpers"
+import { classPrefixCondition, queryInteger, sampleUser } from "../helpers"
 
 export const adminAccountRoutes = new Hono<AppEnv>()
 
@@ -130,7 +130,11 @@ adminAccountRoutes.get("/rankings/users", requireSuperAdmin, async (c) => {
   const where = and(
     inArray(schema.user.adminType, [...STUDENT_ROLES]),
     eq(schema.user.isDisabled, false),
-    keyword ? ilike(schema.user.username, `%${keyword}%`) : undefined,
+    // 输入班级前缀（ks251）按班级匹配，否则照旧按用户名包含
+    keyword
+      ? (classPrefixCondition(keyword) ??
+          ilike(schema.user.username, `%${keyword}%`))
+      : undefined,
   )
 
   const [totalRows, rows] = await Promise.all([

apps/api/src/routes/admin/conf.ts

@@ -26,7 +26,7 @@ import { failure, parseBody, success } from "../../http"
 import { sniffImageExtension } from "../../services/image"
 import { getWebsiteOptions } from "../../services/options"
 import { dayStart } from "../../time"
-import { queryInteger } from "../helpers"
+import { classPrefixCondition, queryInteger } from "../helpers"
 
 export const adminConfRoutes = new Hono<AppEnv>()
 
@@ -253,14 +253,17 @@ adminConfRoutes.get("/dashboard", requireSuperAdmin, async (c) => {
 
 adminConfRoutes.get("/random-usernames", requireSuperAdmin, async (c) => {
   // 传的是**班级前缀**（形如 ks251），不是班级号 —— 前端输入框写的就是「班级前缀」，
-  // 拿到结果后按这个前缀 split 取姓名。这里按前缀匹配，与旧 istartswith 一致，
-  // 不额外按 className 过滤：那会改变旧行为，而这个功能就是随机点名，宁可宽松
+  // 拿到结果后按这个前缀 split 取姓名。班级前缀走 classPrefixCondition（ks251 不带上
+  // ks2511）；别的形状的输入照旧 istartswith，与旧接口一致
   const classroom = c.req.query("classroom")?.trim()
   if (!classroom) return failure(c, 400, "invalid-request", "需要班级号")
   const rows = await db
     .select({ username: schema.user.username })
     .from(schema.user)
-    .where(ilike(schema.user.username, `${classroom}%`))
+    .where(
+      classPrefixCondition(classroom) ??
+        ilike(schema.user.username, `${classroom}%`),
+    )
     .orderBy(sql`random()`)
     .limit(10)
   return success(