refactor: 一批名不副实的命名改掉（只动一端，不碰契约）

后端：
- getUserByToken → authenticateToken：它会删会话、续 TTL、记在线，不是纯读
- todayStart → dayStart(instant)：本来就接受任意时刻，不只是「今天」
- objectValue → asRecord，删掉 4 份一模一样的私有拷贝和 `as toObject` 别名
- 报错文案 "does not exists" / "Already be a public problem" 改通顺

前端：
- utils/types 里 Contest / User / Problem 三个别名删掉：Contest 原来指后台
  比赛、契约里同名的却是学生侧。现在 Contest = 学生侧、AdminContest = 后台，
  后台用户表单叫 AdminUserForm，题目详情直接用 ProblemDetail
- SubmissionInfo → ContestSubmissionInfo，免得和 submission.info 撞名
- utoa / atou → compressToBase64 / decompressFromBase64（实际是 zlib + base64），
  encode / decode → base64EncodeUtf8 / base64DecodeUtf8
- filterResult → toProblemRow、toProblemListItem → toAdminProblemRow，
  行字段 submission / rate → submissionCount / acRate
- 组件：Modal → AddFromLibraryModal、Form → EditorToolbar、
  ContestEditor → BasicEditor（题单也在用它）、rank 的 Index → RankMedal、
  Name → UserNameCell、Password → PasswordCell、ContestType → ContestAccessTag

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

apps/api/src/websocket.ts

@@ -17,6 +17,7 @@ import {
 } from "./judge/events"
 import { JudgeStatus } from "./judge/status"
 import { createSubscriberRedis } from "./redis"
+import { asRecord } from "./routes/helpers"
 import {
   configTopic,
   configUpdateChannel,
@@ -204,12 +205,6 @@ export function startSessionSweep() {
   return timer
 }
 
-function objectValue(value: unknown): Record<string, unknown> {
-  return value && typeof value === "object" && !Array.isArray(value)
-    ? (value as Record<string, unknown>)
-    : {}
-}
-
 export function submissionWebSocketHandler(): Bun.WebSocketHandler<SubmissionSocketData> {
   return {
     open(ws) {
@@ -386,7 +381,7 @@ async function handleMessage(
     return
   }
 
-  const statistics = objectValue(submission.statisticInfo)
+  const statistics = asRecord(submission.statisticInfo)
   const status =
     submission.result === JudgeStatus.PENDING
       ? "pending"