fix(single): fill slide and video cover media like the image cover

Slide-mode images rendered at intrinsic ratio, top-aligned inside the
swiper chain (--pc-height:auto left .swiper-wrapper content-sized), so
the taller box showed a gap at the bottom and never center-cropped like
the image cover. The video cover had the same problem through
video-player.js (height:auto, capped at 70vh).

- aksrt_render_slider scale mode emits --pc-height/--m-height 100% so
  the wrapper/slide/img chain fills the ratio box and object-fit: cover
  center-crops inside it (same pattern as the .scale-height widgets)
- video-player.js renders the video at height:100% + object-fit:cover;
  with an undimensioned container height:100% degrades to auto,
  matching the previous behavior
- drop the dead .single-cover padding-bottom rules (every producer owns
  its height inline, and the rule squeezed the absolutely positioned
  slide inner) and the orphaned --single-cover-scale var in
  tokens.css/compat-vars.css/main.css/InlineStyleBuilder
- rebuild public bundles; extend the single-cover-height contract

assets/css/build/public.css

@@ -214,7 +214,6 @@ Full admin panel preserved (settings, OAuth, content tools, etc).
   --color-primary-dark: var(--color-primary-active);
   --shadow-md:          var(--shadow);
   --mini-radius:        calc(var(--radius) / 1.4);
-  --single-cover-scale: 35%;
 
   /* ===== Avatar size system — legacy --this-size 等价 ===== */
   --aksrt-avatar-size-xs:   24px;

assets/css/core/tokens.css

@@ -189,7 +189,6 @@
   --color-primary-dark: var(--color-primary-active);
   --shadow-md:          var(--shadow);
   --mini-radius:        calc(var(--radius) / 1.4);
-  --single-cover-scale: 35%;
 
   /* ===== Avatar size system — legacy --this-size 等价 ===== */
   --aksrt-avatar-size-xs:   24px;

assets/css/frontend/compat-vars.css

@@ -62,7 +62,6 @@
   /* Cards — 对齐 legacy 70% */
   --posts-card-scale: 70%;
   --posts-list-scale: 70%;
-  --single-cover-scale: 35%;
 }
 
 /* legacy --this-* context-coloring DEFAULTS live with the .but system in

assets/css/frontend/single-post/cover.css

@@ -4,14 +4,14 @@
  * ============================================================ */
 
 /* ===== Cover (in-column ratio box) — legacy .single-cover ===== */
+/* 高度由各模式的内联 padding-bottom 决定；此处不得再声明 padding-bottom，
+ * 否则会挤压绝对定位轮播内层（同样挂 .single-cover 类）的 content box。 */
 .single-cover {
     position: relative;
     overflow: hidden;
     border-radius: var(--main-radius, var(--radius, 8px));
     box-shadow: 0 0 10px var(--main-shadow, rgba(116, 116, 116, 0.08));
     margin-bottom: 20px;
-    /* legacy: padding-bottom: calc(var(--single-cover-scale) + 50px) */
-    padding-bottom: calc(var(--single-cover-scale, 35%) + 50px);
 }
 
 .single-cover > .fit-cover,

assets/css/main.css

@@ -2,7 +2,6 @@ body {
     --mian-max-width: 1200px;
     --posts-card-scale: 70%;
     --posts-list-scale: 70%;
-    --single-cover-scale: 35%;
 
     --theme-color: #f04494;
     --focus-color: var(--theme-color);
@@ -8497,10 +8496,6 @@ body.modal-open .float-btn.wait-pay-btn .hover-show-con {
     margin-left: 50px;
 }
 
-.single-cover {
-    padding-bottom: calc(var(--single-cover-scale) + 50px);
-}
-
 .single-cover-con {
     color: #fff;
     padding: 15px 15px 10px 15px;

assets/js/video-player.js

@@ -28,7 +28,9 @@
     style.id = STYLE_ID;
     style.textContent =
       '.aksrt-video{position:relative;background:#000;border-radius:12px;overflow:hidden;cursor:pointer;}' +
-      '.aksrt-video video{display:block;width:100%;height:auto;max-height:70vh;}' +
+      // 组件容器（文章封面比例盒）有确定高度：视频铺满并居中裁切，对齐单图封面；
+      // 容器无确定高度时 height:100% 退化为 auto，行为与原 height:auto 一致。
+      '.aksrt-video video{display:block;width:100%;height:100%;object-fit:cover;}' +
       '.aksrt-video__overlay{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:rgba(0,0,0,0.3);transition:opacity 0.3s;pointer-events:none;}' +
       '.aksrt-video.is-playing .aksrt-video__overlay{opacity:0;}' +
       '.aksrt-video__play{width:60px;height:60px;border-radius:50%;background:rgba(255,255,255,0.9);display:flex;align-items:center;justify-content:center;font-size:24px;color:#1a1a2e;box-shadow:0 4px 20px rgba(0,0,0,0.3);transition:transform 0.2s;}' +