fix(video): guard sourceless player play attempts

tests/widget-system/single-cover-height-contract.test.cjs

@@ -101,6 +101,20 @@ test('video cover: the player video fills and center-crops like the image cover'
   );
 });
 
+test('video cover: play never runs against a sourceless player', () => {
+  const player = read('assets/js/video-player.js');
+  // toggle 必须先守卫无源状态，且 play() 的 promise 必须被捕获。
+  assert.match(player, /hasSource\s*=\s*function\s*\(\)\s*\{[^}]*currentSrc[^}]*\}/);
+  assert.match(player, /toggle\s*=\s*function\s*\(\)\s*\{\s*if\s*\(!this\.hasSource\(\)\)\s*return;/);
+  assert.match(player, /this\.video\.play\(\)\.catch\(function/);
+  // hls/flv CDN 脚本加载失败必须收敛，不得产生未处理 rejection。
+  assert.match(player, /loadScript\(HLS_SRC\)\.then\([\s\S]*?\}\)\.catch\(function/);
+  assert.match(player, /loadScript\(FLV_SRC\)\.then\([\s\S]*?\}\)\.catch\(function/);
+  // iframe 剧集归 runtime main 的 .switch-iframe 链路，播放器不得接管其选择器。
+  assert.doesNotMatch(player, /closest\('\.switch-video, \.switch-iframe'\)/);
+  assert.doesNotMatch(player, /querySelectorAll\('\.switch-video, \.switch-iframe'\)/);
+});
+
 test('resource singles get the cover leaf versioned, never via the aggregate @import', () => {
   // 聚合文件的 @import 无版本号：浏览器会拿旧缓存（含已废弃的 .single-cover
   // padding 规则）把封面高度链挤成 0，资源型文章封面直接空白。