main: 用户管理和会话功能初始实现

- 添加用户管理功能的测试，包括创建、更新、停用、激活用户及用户登录 JWT 测试
- 提供用户管理相关的请求验证类与控制器
- 引入 CORS 配置信息，支持跨域请求
- 添加数据库播种器以便创建根用户
- 配置 API 默认使用 JWT 认证
- 添加聊天会话和消息的模型、迁移文件及关联功能

app/Http/Controllers/UserController.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Http\Controllers;
+
+use App\Http\Requests\StoreUserRequest;
+use App\Http\Requests\UpdateUserRequest;
+use App\Http\Resources\UserResource;
+use App\Models\User;
+use Illuminate\Http\JsonResponse;
+use Illuminate\Http\Request;
+
+class UserController extends Controller
+{
+    public function index(Request $request): JsonResponse
+    {
+        $perPage = (int) $request->query('per_page', 15);
+        $perPage = $perPage > 0 && $perPage <= 100 ? $perPage : 15;
+
+        $users = User::orderBy('id')->paginate($perPage);
+
+        return UserResource::collection($users)->response();
+    }
+
+    public function store(StoreUserRequest $request): JsonResponse
+    {
+        $payload = $request->validated();
+        $payload['is_active'] = true;
+
+        $user = User::create($payload);
+
+        return (new UserResource($user))->response()->setStatusCode(201);
+    }
+
+    public function update(UpdateUserRequest $request, User $user): JsonResponse
+    {
+        $user->update($request->validated());
+
+        return (new UserResource($user))->response();
+    }
+
+    public function deactivate(User $user): JsonResponse
+    {
+        $user->update(['is_active' => false]);
+
+        return (new UserResource($user))->response();
+    }
+
+    public function activate(User $user): JsonResponse
+    {
+        $user->update(['is_active' => true]);
+
+        return (new UserResource($user))->response();
+    }
+}