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/flowchart.ts

@@ -0,0 +1,71 @@
+import { z } from "zod"
+
+import { paginatedSchema } from "./common"
+
+export const flowchartStatusSchema = z.union([z.literal(0), z.literal(1), z.literal(2), z.literal(3)])
+
+export const createFlowchartRequestSchema = z.object({
+  problemId: z.number().int().positive(),
+  mermaidCode: z.string().trim().min(1).max(50_000).refine(
+    (value) => value.split("\n").filter((line) => line.trim()).length <= 200,
+    "Flowchart is too complex",
+  ),
+  flowchartData: z.record(z.string(), z.unknown()).default({}),
+})
+
+export const flowchartSubmissionSchema = z.object({
+  id: z.string(),
+  username: z.string(),
+  problemId: z.number().int(),
+  mermaidCode: z.string(),
+  flowchartData: z.record(z.string(), z.unknown()),
+  status: flowchartStatusSchema,
+  createTime: z.string(),
+  aiScore: z.number().nullable(),
+  aiGrade: z.string().nullable(),
+  aiFeedback: z.string().nullable(),
+  aiSuggestions: z.string().nullable(),
+  aiCriteriaDetails: z.record(z.string(), z.unknown()),
+  aiProvider: z.string(),
+  aiModel: z.string(),
+  processingTime: z.number().nullable(),
+  evaluationTime: z.string().nullable(),
+})
+
+export const flowchartListItemSchema = z.object({
+  id: z.string(),
+  username: z.string(),
+  problem: z.string(),
+  problemTitle: z.string(),
+  status: flowchartStatusSchema,
+  createTime: z.string(),
+  aiScore: z.number().nullable(),
+  aiGrade: z.string().nullable(),
+  aiProvider: z.string(),
+  aiModel: z.string(),
+  processingTime: z.number().nullable(),
+  evaluationTime: z.string().nullable(),
+  showLink: z.boolean(),
+})
+
+export const flowchartListSchema = paginatedSchema(flowchartListItemSchema)
+export const createFlowchartResponseSchema = z.object({ submissionId: z.string(), status: z.literal("pending") })
+export const flowchartCurrentSchema = z.object({ count: z.number().int(), score: z.number(), grade: z.string() })
+export const flowchartDetailSchema = z.object({ submission: flowchartSubmissionSchema.nullable(), count: z.number().int() })
+
+export const flowchartUpdateSchema = z.object({
+  type: z.enum([
+    "flowchart_evaluation_completed",
+    "flowchart_evaluation_failed",
+    "flowchart_evaluation_update",
+  ]),
+  submission_id: z.string(),
+  score: z.number().optional(),
+  grade: z.string().optional(),
+  feedback: z.string().optional(),
+  suggestions: z.string().optional(),
+  criteriaDetails: z.unknown().optional(),
+  error: z.string().optional(),
+})
+
+export type FlowchartUpdate = z.infer<typeof flowchartUpdateSchema>