refactor(api): 请求体解析收成 readJson / parseBody

54 处 handler 都手写同一段：
  const parsed = X.safeParse(await c.req.json().catch(() => null))
  if (!parsed.success) return failure(c, 400, "invalid-request", ...)
漏写 .catch 就是一个畸形请求打出 500。

- http.ts 加 readJson（读 + 校验）和 parseBody（再加上 400）。parseBody 不给
  message 时回 zod 的第一条 issue —— 后台表单原来就是这么写的，fallback 文案
  「Invalid payload」/「参数错误」只在 issues 为空时才用得上，实际走不到
- 51 处换成 parseBody；另 3 处失败时带别的错误码或和路径参数一起判，换成 readJson
- 错误码、状态码、文案、判断顺序都不变

实跑核过：非 JSON 请求体回原来的固定文案，公告标题为空回 zod issue。

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

apps/api/src/routes/content.ts

@@ -23,7 +23,7 @@ import { Hono } from "hono"
 
 import { requireAuth, requireSuperAdmin, type AppEnv } from "../auth/middleware"
 import { db, schema } from "../db"
-import { failure, success } from "../http"
+import { failure, parseBody, success } from "../http"
 import { JudgeStatus } from "../judge/status"
 import { objectValue, queryInteger, sampleUser } from "./helpers"
 
@@ -187,11 +187,12 @@ contentRoutes.get("/messages", requireAuth, async (c) => {
  */
 contentRoutes.post("/messages", requireSuperAdmin, async (c) => {
   const user = c.get("user")!
-  const parsed = createMessageRequestSchema.safeParse(
-    await c.req.json().catch(() => null),
+  const parsed = await parseBody(
+    c,
+    createMessageRequestSchema,
+    "Invalid message payload",
   )
-  if (!parsed.success)
-    return failure(c, 400, "invalid-request", "Invalid message payload")
+  if (!parsed.success) return parsed.response
   if (parsed.data.recipientId === user.id)
     return failure(
       c,
@@ -263,11 +264,12 @@ contentRoutes.get("/problems/:id/reaction", requireAuth, async (c) => {
 
 contentRoutes.post("/problems/:id/reaction", requireAuth, async (c) => {
   const problemId = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const parsed = setReactionRequestSchema.safeParse(
-    await c.req.json().catch(() => null),
+  const parsed = await parseBody(
+    c,
+    setReactionRequestSchema,
+    "Invalid reaction",
   )
-  if (!parsed.success)
-    return failure(c, 400, "invalid-request", "Invalid reaction")
+  if (!parsed.success) return parsed.response
   const user = c.get("user")!
   const [[problem], [solved]] = await Promise.all([
     db
@@ -447,11 +449,12 @@ contentRoutes.get("/learn/progress", requireAuth, async (c) => {
 contentRoutes.post("/tutorials/:id/progress", requireAuth, async (c) => {
   const user = c.get("user")!
   const id = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const parsed = tutorialProgressPingSchema.safeParse(
-    await c.req.json().catch(() => null),
+  const parsed = await parseBody(
+    c,
+    tutorialProgressPingSchema,
+    "Invalid progress payload",
   )
-  if (!parsed.success)
-    return failure(c, 400, "invalid-request", "Invalid progress payload")
+  if (!parsed.success) return parsed.response
   const [tutorial] = await db
     .select({ id: schema.tutorial.id })
     .from(schema.tutorial)
@@ -501,11 +504,12 @@ contentRoutes.post("/tutorials/:id/progress", requireAuth, async (c) => {
 contentRoutes.post("/exercises/:id/attempts", requireAuth, async (c) => {
   const user = c.get("user")!
   const id = queryInteger(c.req.param("id"), 0, { min: 1 })
-  const parsed = exerciseAttemptRequestSchema.safeParse(
-    await c.req.json().catch(() => null),
+  const parsed = await parseBody(
+    c,
+    exerciseAttemptRequestSchema,
+    "Invalid attempt payload",
   )
-  if (!parsed.success)
-    return failure(c, 400, "invalid-request", "Invalid attempt payload")
+  if (!parsed.success) return parsed.response
   // 练习跟着教程走：教程没公开，它底下的练习也不该能上报
   const [exercise] = await db
     .select({ id: schema.exercise.id })