feat(tickets): make ticket title/content/reply length limits configurable

Add ticket_title_max / ticket_content_max / ticket_reply_max to the
users/ticket schema (PHP + SPA) with clamped TicketSettings readers.
All write paths (front REST, admin REST, note REST, native admin page)
and front-end maxlength/counters now read the configured limits.
Remove the hardcoded TICKET_CONTENT_MAX constant.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/js/ticket-center.js

@@ -22,6 +22,7 @@
   var settings = core.settings;
   var attachmentEnabled = core.attachmentEnabled;
   var attachmentMax = core.attachmentMax;
+  var lengthMax = core.lengthMax;
   var escapeHtml = core.escapeHtml;
   var notyf = core.notyf;
   var request = core.request;
@@ -448,11 +449,11 @@
       + attachTrayHtml()
       + '<div class="aksrt-ticket-composer__input">'
       + '<label class="screen-reader-text" for="' + fieldId + '">回复内容</label>'
-      + '<textarea id="' + fieldId + '" name="reply" rows="2" maxlength="3000"'
+      + '<textarea id="' + fieldId + '" name="reply" rows="2" maxlength="' + lengthMax('reply') + '"'
       + ' placeholder="补充说明或回复客服…"></textarea></div>'
       + '<div class="aksrt-ticket-composer__bar">'
       + '<span class="aksrt-ticket-composer__hint">Ctrl + Enter 发送</span>'
-      + '<span class="aksrt-ticket-counter" data-aksrt-ticket-counter="reply">0 / 3000</span>'
+      + '<span class="aksrt-ticket-counter" data-aksrt-ticket-counter="reply">0 / ' + lengthMax('reply') + '</span>'
       + '<button type="submit" class="btn-primary" data-aksrt-ticket-submit>' + icon('fa-paper-plane') + '发送</button>'
       + '</div></form>';
   }
@@ -642,8 +643,8 @@
 
     html += field(
       '<label for="aksrt-ticket-f-title">工单标题<em aria-hidden="true">*</em></label>',
-      '<input id="aksrt-ticket-f-title" type="text" name="title" maxlength="200" autocomplete="off" placeholder="一句话概括问题，如：支付成功但会员未开通">',
-      '<span class="aksrt-ticket-counter" data-aksrt-ticket-counter="title">0 / 200</span>'
+      '<input id="aksrt-ticket-f-title" type="text" name="title" maxlength="' + lengthMax('title') + '" autocomplete="off" placeholder="一句话概括问题，如：支付成功但会员未开通">',
+      '<span class="aksrt-ticket-counter" data-aksrt-ticket-counter="title">0 / ' + lengthMax('title') + '</span>'
     );
 
     html += '<fieldset class="aksrt-ticket-field aksrt-ticket-types" data-aksrt-ticket-types>'
@@ -667,8 +668,8 @@
 
     html += field(
       '<label for="aksrt-ticket-f-content">问题描述<em aria-hidden="true">*</em></label>',
-      '<textarea id="aksrt-ticket-f-content" name="content" rows="5" maxlength="5000" placeholder="请描述问题现象、发生时间、操作步骤等，信息越完整处理越快"></textarea>',
-      '<span class="aksrt-ticket-counter" data-aksrt-ticket-counter="content">0 / 5000</span>'
+      '<textarea id="aksrt-ticket-f-content" name="content" rows="5" maxlength="' + lengthMax('content') + '" placeholder="请描述问题现象、发生时间、操作步骤等，信息越完整处理越快"></textarea>',
+      '<span class="aksrt-ticket-counter" data-aksrt-ticket-counter="content">0 / ' + lengthMax('content') + '</span>'
     );
 
     if (attachmentEnabled()) {