永久会员与模板库后台化：预览门控、轻量首页与 Admin CRUD

- 会员改为永久激活方案；云端文件不再拦截非会员；预览弹窗内导出/打印才校验
- 首页最近文件支持本地记录，登录后与云端合并；移除独立会员页与订阅页
- 模板库入库管理：soon_templates 表、Admin 上传 CRUD、/templates 轻量列表与按需下载

Co-authored-by: Cursor <cursoragent@cursor.com>

backend-web/src/Controllers/FileController.php

@@ -6,7 +6,6 @@ namespace Soon\Api\Controllers;
 use Soon\Api\Core\Json;
 use Soon\Api\Middleware\Auth;
 use Soon\Api\Services\FileService;
-use Soon\Api\Services\MembershipService;
 
 final class FileController
 {
@@ -39,7 +38,6 @@ final class FileController
     public function create(): void
     {
         $u = Auth::require();
-        MembershipService::requireActiveMember($u['id']);
         $body = Json::readBody();
         $name = (string)($body['name'] ?? 'untitled.soon');
         $json = (string)($body['json'] ?? '{}');
@@ -49,7 +47,6 @@ final class FileController
     public function update(int $id): void
     {
         $u = Auth::require();
-        MembershipService::requireActiveMember($u['id']);
         $body = Json::readBody();
         $name = (string)($body['name'] ?? 'untitled.soon');
         $json = (string)($body['json'] ?? '{}');
@@ -67,12 +64,6 @@ final class FileController
     public function download(int $id): void
     {
         $u = Auth::require();
-        $accept = (string)($_SERVER['HTTP_ACCEPT'] ?? '');
-        $jsonRead = stripos($accept, 'application/json') !== false
-            && stripos($accept, 'application/octet-stream') === false;
-        if (!$jsonRead) {
-            MembershipService::requireActiveMember($u['id']);
-        }
         $row = FileService::fetch($u['id'], $id);
         $name = (string)$row['name'];
         $json = (string)$row['json'];