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/css/frontend/modal-runtime.css

@@ -223,6 +223,23 @@ body.aksrt-modal-runtime-open {
   color: var(--color-on-primary, #fff);
 }
 
+/* ---- 签到详情弹窗（参考主题 refresh_modal modal-mini 同构壳） ----
+   内容为服务端 HTML（modal-colorful-header + modal-body），与参考主题
+   .modal-dialog.modal-mini 几何 1:1：宽 400px、圆角 var(--main-radius)。 */
+.aksrt-modal-runtime.aksrt-checkin-details-modal:not(.aksrt-modal-runtime--bottom) .aksrt-modal-runtime__dialog {
+  width: min(400px, calc(100vw - 32px));
+  border-radius: var(--main-radius, 8px);
+  background: var(--main-bg-color, #fff);
+}
+
+.aksrt-modal-runtime.aksrt-checkin-details-modal .aksrt-modal-runtime__content {
+  padding: 0;
+}
+
+.aksrt-modal-runtime.aksrt-checkin-details-modal .aksrt-modal-runtime__skeleton {
+  padding: 24px 18px;
+}
+
 /* ---- ajax list ---- */
 .ajaxpager.is-ajax-loading {
   position: relative;