fix: settings modal dismiss — add close button, fix backdrop click

muxplex/frontend/style.css

@@ -934,15 +934,51 @@ body {
   padding: 0;
   overflow: hidden;
   margin: 0;
+  display: flex;
+  flex-direction: column;
 }
 
 .settings-dialog::backdrop {
   background: transparent;
+  pointer-events: none;  /* let clicks fall through to #settings-backdrop */
+}
+
+.settings-dialog-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding: 10px 16px;
+  border-bottom: 1px solid var(--border);
+  flex-shrink: 0;
+}
+
+.settings-dialog-title {
+  margin: 0;
+  font-size: 14px;
+  font-weight: 600;
+  color: var(--text);
+}
+
+.settings-close-btn {
+  background: none;
+  border: none;
+  color: var(--text-muted);
+  font-size: 20px;
+  cursor: pointer;
+  padding: 2px 6px;
+  border-radius: 4px;
+  line-height: 1;
+}
+
+.settings-close-btn:hover {
+  color: var(--text);
+  background: var(--bg-surface);
 }
 
 .settings-layout {
   display: flex;
-  height: 100%;
+  flex: 1;
+  min-height: 0;
 }
 
 .settings-tabs {