feat(attachment): 按参考主题重构后台上传配置套件

- 新增 AKSRT\Attachment\UploadLimits：按用户类型解析图片/视频/文件
  上传上限（取最大值+默认兜底，钳制到 PHP 上限）、允许/禁止格式过滤、
  上传自动重命名、非管理员附件页 404；不含论坛角色
- 后台「附件配置」重做：大小限制/格式限制/上传行为三组配置，
  PHP Schema 与 SPA Schema 逐字段镜像（v1.2.0）
- 定制页 AttachmentPermissions.vue 改为标准 schemaPage，清理失效的
  API 包装、组件加载器与旧配置键（submit_image_max_size 等）
- 投稿/评论上传、批量上传数量全部切换到新链路；AksField 数字组件
  支持单位展示
- 更新 captcha harness 与 front-submit 契约测试；421 项测试通过

src/Core/FrontSubmit.php

@@ -118,18 +118,13 @@ class FrontSubmit {
     }
 
     public static function upload_limit_bytes(string $kind): int {
-        $settings = class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::get_all() : [];
-        $configured_mb = match ($kind) {
-            'image'    => max(1, min(20, (int) ($settings['submit_image_max_size'] ?? 5))),
-            'video'    => max(1, min(200, (int) ($settings['submit_video_max_size'] ?? 30))),
-            'resource' => max(1, min(200, (int) ($settings['resource_max_size'] ?? 50))),
-            default    => 0,
-        };
-        if ($configured_mb === 0) {
-            return 0;
+        // Kind names follow the REST route; the config rows use the reference
+        // theme's naming (image / video / file).
+        $config_kind = $kind === 'resource' ? 'file' : $kind;
+        if (class_exists('\AKSRT\Attachment\UploadLimits')) {
+            return \AKSRT\Attachment\UploadLimits::limit_bytes($config_kind);
         }
-
-        return min($configured_mb * MB_IN_BYTES, (int) wp_max_upload_size());
+        return (int) wp_max_upload_size();
     }
 
     public function rest_upload_attachment(\WP_REST_Request $request) {

src/Core/ScriptsPart1c.php

@@ -479,9 +479,9 @@ trait ScriptsPart1c {
             'commentIasAuto'        => class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::get_comment_display_settings()['paging_ajax_ias'] : true,
             'commentUploadUrl'       => esc_url_raw(rest_url('aksrt/v1/comment/upload-image')),
             'commentUploadMaxSize'   => (function () {
-                $settings = class_exists('\\AKSRT\\Settings\\Settings') ? \AKSRT\Settings\Settings::get_all() : [];
-                $max_size_mb = max(1, min(10, (int) ($settings['comment_image_max_size'] ?? 2)));
-                return $max_size_mb * MB_IN_BYTES;
+                return class_exists('\AKSRT\Attachment\UploadLimits')
+                    ? \AKSRT\Attachment\UploadLimits::limit_bytes('image')
+                    : (int) wp_max_upload_size();
             })(),
             'commentIasMax'         => class_exists('\AKSRT\Settings\Settings') ? \AKSRT\Settings\Settings::get_comment_display_settings()['paging_ajax_ias_max'] : 3,
             'restUrl'               => esc_url_raw(rest_url('aksrt/v1')),