refactor: 引入 apiHandler + ApiError，消除 20 个路由的 try/catch 样板

- 新增 src/lib/api.ts：ApiError 错误类 + apiHandler 统一包装器
- 20 个 API 路由统一使用 apiHandler，删除重复的 try/catch 块
- 验证错误改用 throw new ApiError()，减少嵌套层级
- join/manage 路由的错误码映射改为直接抛出 ApiError
- 删除已无引用的 errorResponse 辅助函数
- 净减 273 行代码

src/app/api/user/route.ts

@@ -1,17 +1,14 @@
-import { NextRequest, NextResponse } from "next/server";
+import { NextResponse } from "next/server";
 import { prisma } from "@/lib/prisma";
 import bcrypt from "bcryptjs";
+import { apiHandler, ApiError } from "@/lib/api";
 
-export async function GET(req: NextRequest) {
+export const GET = apiHandler(async (req) => {
   const userId = req.nextUrl.searchParams.get("id");
-  if (!userId) {
-    return NextResponse.json(null);
-  }
+  if (!userId) return NextResponse.json(null);
 
   const user = await prisma.user.findUnique({ where: { id: userId } });
-  if (!user) {
-    return NextResponse.json(null);
-  }
+  if (!user) return NextResponse.json(null);
 
   const decisionCount = await prisma.decision.count({ where: { userId } });
 
@@ -24,48 +21,36 @@ export async function GET(req: NextRequest) {
     createdAt: user.createdAt.toISOString(),
     decisionCount,
   });
-}
+});
 
-export async function PUT(req: NextRequest) {
+export const PUT = apiHandler(async (req) => {
   const body = await req.json();
   const { userId } = body;
 
-  if (!userId) {
-    return NextResponse.json({ error: "缺少用户 ID" }, { status: 400 });
-  }
+  if (!userId) throw new ApiError("缺少用户 ID");
 
   const existing = await prisma.user.findUnique({ where: { id: userId } });
-  if (!existing) {
-    return NextResponse.json({ error: "用户不存在" }, { status: 404 });
-  }
+  if (!existing) throw new ApiError("用户不存在", 404);
 
   const updateData: Record<string, unknown> = {};
 
   if (body.username !== undefined) {
     const trimmed = body.username.trim();
     if (trimmed.length < 2 || trimmed.length > 16) {
-      return NextResponse.json({ error: "用户名需要 2-16 个字符" }, { status: 400 });
+      throw new ApiError("用户名需要 2-16 个字符");
     }
     if (trimmed !== existing.username) {
       const taken = await prisma.user.findUnique({ where: { username: trimmed } });
-      if (taken) {
-        return NextResponse.json({ error: "用户名已被占用" }, { status: 409 });
-      }
+      if (taken) throw new ApiError("用户名已被占用", 409);
     }
     updateData.username = trimmed;
   }
 
   if (body.newPassword !== undefined) {
-    if (!body.currentPassword) {
-      return NextResponse.json({ error: "请输入当前密码" }, { status: 400 });
-    }
+    if (!body.currentPassword) throw new ApiError("请输入当前密码");
     const valid = await bcrypt.compare(body.currentPassword, existing.passwordHash);
-    if (!valid) {
-      return NextResponse.json({ error: "当前密码错误" }, { status: 403 });
-    }
-    if (body.newPassword.length < 6) {
-      return NextResponse.json({ error: "新密码至少 6 个字符" }, { status: 400 });
-    }
+    if (!valid) throw new ApiError("当前密码错误", 403);
+    if (body.newPassword.length < 6) throw new ApiError("新密码至少 6 个字符");
     updateData.passwordHash = await bcrypt.hash(body.newPassword, 10);
   }
 
@@ -75,7 +60,7 @@ export async function PUT(req: NextRequest) {
 
   if (body.email !== undefined) {
     if (body.email && !/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(body.email)) {
-      return NextResponse.json({ error: "邮箱格式不正确" }, { status: 400 });
+      throw new ApiError("邮箱格式不正确");
     }
     updateData.email = body.email || null;
   }
@@ -96,4 +81,4 @@ export async function PUT(req: NextRequest) {
     email: user.email,
     preferences: JSON.parse(user.preferences),
   });
-}
+});