feat: webapp topbar and tab switching

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

@@ -130,3 +130,98 @@ body {
   border: 1px solid var(--glass-border);
   color: var(--text-dim);
 }
+
+/* webAPP 顶栏：浮层玻璃条 + 标签面板 */
+/* webapp topbar: floating glass bar + tab panel */
+#web-topbar {
+  position: fixed;
+  top: 12px;
+  left: 50%;
+  transform: translateX(-50%);
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 6px 10px;
+  border-radius: 999px;
+  background: var(--glass-bg);
+  backdrop-filter: blur(20px) saturate(1.2);
+  -webkit-backdrop-filter: blur(20px) saturate(1.2);
+  border: 1px solid var(--glass-border);
+  z-index: 100;
+}
+
+#web-topbar button {
+  width: 30px;
+  height: 30px;
+  border: none;
+  border-radius: 999px;
+  background: none;
+  color: var(--text);
+  font-size: 16px;
+  cursor: pointer;
+}
+
+#web-topbar button:active { background: var(--glass-border); }
+
+#web-topbar #tb-tabs {
+  width: auto;
+  padding: 0 12px;
+  font-size: 13px;
+  color: var(--text-dim);
+}
+
+#web-topbar .tb-title {
+  max-width: 200px;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  font-size: 14px;
+  color: var(--text);
+}
+
+#tab-panel {
+  position: fixed;
+  top: 56px;
+  right: 16px;
+  display: none;
+  min-width: 180px;
+  max-width: 260px;
+  padding: 8px;
+  border-radius: 16px;
+  background: var(--glass-bg);
+  backdrop-filter: blur(20px) saturate(1.2);
+  -webkit-backdrop-filter: blur(20px) saturate(1.2);
+  border: 1px solid var(--glass-border);
+  z-index: 100;
+}
+
+#tab-panel .tab-row {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 8px;
+  padding: 8px 10px;
+  border-radius: 10px;
+  cursor: pointer;
+}
+
+#tab-panel .tab-row.active { background: var(--accent); color: #fff; }
+
+#tab-panel .tab-name {
+  flex: 1;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  font-size: 13px;
+}
+
+#tab-panel .tab-close {
+  border: none;
+  background: none;
+  color: inherit;
+  font-size: 16px;
+  cursor: pointer;
+  opacity: 0.7;
+}
+
+#tab-panel .tab-close:hover { opacity: 1; }