fix: visible music-icon placeholder when media has no cover

app/src/main/assets/h5/css/app.css

@@ -249,7 +249,16 @@ body {
 }
 
 .media-card .cover-ph {
-  background: linear-gradient(135deg, rgba(255, 255, 255, .15), rgba(255, 255, 255, .05));
+  background: linear-gradient(135deg, var(--accent), rgba(255, 157, 0, .6));
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  color: #fff;
+}
+
+.media-card .cover-ph svg {
+  width: 40%;
+  height: 40%;
 }
 
 .media-card.wide .cover {

app/src/main/assets/h5/js/pages/home.js

@@ -180,7 +180,7 @@ function renderMediaCard(info) {
   el.className = 'card media-card';
   const coverHtml = info.cover
     ? `<img class="cover" src="${info.cover}" alt="">`
-    : '<div class="cover cover-ph"></div>';
+    : '<div class="cover cover-ph"><svg viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.6" stroke-linecap="round" stroke-linejoin="round"><path d="M9 18V6l12-2v12"/><circle cx="6" cy="18" r="3"/><circle cx="18" cy="16" r="3"/></svg></div>';
   const playIcon = info.playing ? ICON_PAUSE : ICON_PLAY;
   // title/artist 来自任意应用元数据，转义后插入，防 XSS
   // title/artist come from arbitrary app metadata; escape before insert (XSS)