feat(devices): 设备列表增加国家筛选项

与访问记录列表实现保持一致：
- DeviceController::index() 向视图传入 countries (CfIpCountry::names())
- filtersFrom() 解析 country 参数 (CfIpCountry::normalize，支持 ISO 代码与中文名)
- filteredQuery() 按 devices.country 过滤
- 视图在 iOS 版本与钱包之间新增 lay-search 国家下拉框
- 重置按钮 reload where 增加 country: ''

resources/views/admin/devices/index.blade.php

@@ -43,6 +43,17 @@
           <input type="text" name="ios" placeholder="15.8" autocomplete="off" class="layui-input">
         </div>
       </div>
+      <div class="layui-inline">
+        <label class="layui-form-label">国家</label>
+        <div class="layui-input-block" style="min-width: 180px;">
+          <select name="country" lay-search>
+            <option value="">全部</option>
+            @foreach ($countries as $code => $name)
+              <option value="{{ $code }}">{{ $name }} ({{ $code }})</option>
+            @endforeach
+          </select>
+        </div>
+      </div>
       <div class="layui-inline">
         <label class="layui-form-label">钱包</label>
         <div class="layui-input-block">
@@ -220,6 +231,7 @@ layui.use(['table', 'form', 'laydate', 'layer'], function () {
           model: '',
           ip: '',
           ios: '',
+          country: '',
           has_wallet: '',
           has_im: '',
           installed_from: '',