feat(checkin): open reference-parity details modal from signed buttons

- Rebuild checkin details modal HTML 1:1 with reference theme:
  colorful header c-blue, user card (points/level), daily reward
  card and 7-day continuous mini cards
- Signed entry buttons (header dropdown, user-card badge, user
  center) become clickable checkin-details-link modal triggers
  instead of disabled buttons
- Swap data-signin-btn to details link in place after successful
  signin (reference .initiate-checkin replacement behavior)
- Add aksrt-checkin-details-modal runtime shell (modal-mini 400px)
- Remove dead code: legacy lite modal, admin-ajax details handler,
  /signin/history route, signin calendar; rebuild public bundles
- Update contract tests to the new checkin modal contract

assets/js/signin.js

@@ -72,6 +72,26 @@
       });
     }
 
+    // 签到成功后，入口按钮就地替换为「已签到」详情弹窗触发链接
+    // （参考主题：.initiate-checkin → details_link 的替换行为）。
+    function swapButtonsToDetailsLink() {
+      var url = window.aksrtData && window.aksrtData.signinDetailsUrl;
+      if (!url) return;
+      currentButtons().forEach(function (button) {
+        var link = document.createElement('a');
+        link.href = 'javascript:;';
+        link.className = (button.className || '') + ' checkin-details-link';
+        link.setAttribute('data-aksrt-modal', 'remote');
+        link.setAttribute('data-aksrt-modal-url', url);
+        link.setAttribute('data-aksrt-modal-class', 'aksrt-checkin-details-modal modal-mini');
+        link.setAttribute('data-aksrt-modal-height', '240');
+        link.setAttribute('data-aksrt-modal-mobile-bottom', 'true');
+        link.setAttribute('data-aksrt-modal-cache', 'false');
+        link.innerHTML = button.innerHTML;
+        button.replaceWith(link);
+      });
+    }
+
     function refresh() {
       api('/signin/today').then(function (result) {
         if (!result.ok) {
@@ -90,6 +110,7 @@
         if (data.signed) {
           setStatusHtml('已签到 <strong>' + data.streak + '</strong> 天 +' + data.reward_today);
           setButtonState('done');
+          swapButtonsToDetailsLink();
           return;
         }
         setStatusHtml('连续 <strong>' + data.streak + '</strong> 天，+' + data.reward_if_signin);
@@ -120,6 +141,7 @@
           element.title = element.textContent;
         });
         setButtonState('done');
+        swapButtonsToDetailsLink();
         refresh();
       }).finally(function () {
         if (window.AKSRTCaptcha) window.AKSRTCaptcha.reset('signin', captchaMount());