fix(single): match the reference video cover height (bare ratio)

Zibll reserves +50px only for covers whose title overlays them
(image/slide via .single-cover/.single-cover-slide); the video cover
keeps its title in the footer below and uses the bare scale height
(.dplayer-scale-height). Drop the +50px from the video box, pin the
reference height matrix in the contract test, and refresh the stale
slide-action assertion in the toast contract.

tests/widget-system/toast-contract.test.cjs

@@ -388,9 +388,10 @@ test('front submit actions use direct fixed-id notyf flows', () => {
   assert.match(submit, /submit: function[\s\S]*?notyf\([^;]+?'load'[^;]+?toastId[\s\S]*?notyf\([^;]+?'success'[^;]+?toastId[\s\S]*?notyf\([^;]+?'danger'[^;]+?toastId/);
   assert.match(submit, /bindDraftDelete: function[\s\S]*?'aksrt-front-submit-delete-draft-toast'[\s\S]*?'load'[\s\S]*?'success'[\s\S]*?'danger'/);
 
-  // 封面（单图/多图/视频封面）选择统一走 AksrtSubmitMedia 选择器，
-  // 上传中的 load/success/danger 通知由选择器以固定 id 独立承载。
-  ['image', 'slide', 'video'].forEach((type) => {
+  // 封面（单图/多图共用 image 入口、视频封面、视频）选择统一走
+  // AksrtSubmitMedia 选择器，上传中的 load/success/danger 通知由选择器
+  // 以固定 id 独立承载；幻灯片动作已并入 image 多选，无独立分支。
+  ['image', 'video_pic', 'video'].forEach((type) => {
     assert.match(submit, new RegExp("act === '" + type + "'[\\s\\S]{0,400}?self\\.openMediaPicker\\("));
   });
   assert.match(editor, /var toastId = 'aksrt-front-submit-editor-media-toast';/);