feat(阶段3): oj 侧端点铺开（基线提交，未经评审）

由外部 agent (Codex) 在本会话额度中断期间完成。原样提交作为基线，
后续修复单独成 commit，便于区分与回退。

覆盖 oj 侧 65 个端点，新增 9 组路由（account/achievement/ai/classroom/
content/contest/flowchart/problemset/site）与对应 Zod 契约。

已核验：tsc --noEmit 退出码 0；API 可启动；/api/problems 返回真实数据；
judge 与 flowchart worker 均 ready。
未核验：权限边界与数据泄露，评审进行中。

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

packages/contract/src/submission.ts

@@ -1,5 +1,7 @@
 import { z } from "zod"
 
+import { paginatedSchema } from "./common"
+
 export const judgeStatusSchema = z.union([
   z.literal(-2),
   z.literal(-1),
@@ -55,6 +57,31 @@ export const submissionUpdateSchema = z.object({
   err_info: z.string().optional(),
 })
 
+export const submissionListItemSchema = z.object({
+  id: z.string(),
+  problem: z.string(),
+  problemTitle: z.string(),
+  showLink: z.boolean(),
+  createTime: z.string(),
+  userId: z.number().int(),
+  username: z.string(),
+  result: judgeStatusSchema,
+  language: z.string(),
+  shared: z.boolean(),
+  statisticInfo: z.record(z.string(), z.unknown()),
+})
+
+export const submissionListSchema = paginatedSchema(submissionListItemSchema)
+
+export const shareSubmissionRequestSchema = z.object({ shared: z.boolean() })
+
+export const formatCodeRequestSchema = z.object({
+  code: z.string().max(1024 * 1024),
+  language: z.enum(["python", "c", "cpp", "sql"]),
+})
+
+export const formatCodeResponseSchema = z.object({ code: z.string() })
+
 export type JudgeStatus = z.infer<typeof judgeStatusSchema>
 export type CreateSubmissionRequest = z.infer<
   typeof createSubmissionRequestSchema