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>

apps/api/src/routes/site.ts

@@ -0,0 +1,47 @@
+import { quoteSchema, websiteConfigSchema } from "@oj2/contract"
+import { asc, desc, eq } from "drizzle-orm"
+import { Hono } from "hono"
+
+import { db, schema } from "../db"
+import { failure, success } from "../http"
+import { getWebsiteOptions } from "../services/options"
+
+export const siteRoutes = new Hono()
+
+siteRoutes.get("/site", async (c) => {
+  const options = await getWebsiteOptions()
+  return success(c, websiteConfigSchema.parse({
+    websiteBaseUrl: options.website_base_url,
+    websiteName: options.website_name,
+    websiteNameShortcut: options.website_name_shortcut,
+    websiteFooter: options.website_footer,
+    allowRegister: options.allow_register,
+    submissionListShowAll: options.submission_list_show_all,
+    classList: options.class_list,
+    enableMaxkb: options.enable_maxkb,
+  }))
+})
+
+const quotes = [
+  { hitokoto: "程序首先是写给人读的，其次才是让机器执行。", from: "Structure and Interpretation of Computer Programs" },
+  { hitokoto: "把大问题拆成足够小的问题，答案就会浮现。", from: "判题狗" },
+  { hitokoto: "一次没通过，只是多得到了一条线索。", from: "判题狗" },
+]
+
+siteRoutes.get("/quotes/random", (c) => {
+  const item = quotes[Math.floor(Math.random() * quotes.length)] ?? quotes[0]
+  return success(c, quoteSchema.parse(item))
+})
+
+siteRoutes.get("/classes/:className/usernames", async (c) => {
+  const className = c.req.param("className").trim()
+  if (!/^\d{3,4}$/.test(className)) {
+    return failure(c, 400, "invalid-class", "Class name must contain 3 or 4 digits")
+  }
+  const rows = await db
+    .select({ username: schema.user.username })
+    .from(schema.user)
+    .where(eq(schema.user.className, className))
+    .orderBy(desc(schema.user.createTime), asc(schema.user.id))
+  return success(c, rows.map(({ username }) => username.replace(`ks${className}`, "")))
+})