feat(ui): add microphone mute control

s2s-client/style.css

@@ -542,6 +542,8 @@ a:hover {
     0 0 34px -6px color-mix(in srgb, var(--brand) 60%, transparent);
 }
 #ident-user-name[hidden],
+#white-session-controls[hidden],
+#white-mute-btn[hidden],
 #white-stop-btn[hidden],
 #white-mic-subcaption[hidden] {
   display: none !important;
@@ -4623,6 +4625,7 @@ html[data-theme="white"] .white-mic-circle:disabled {
   cursor: default;
 }
 html[data-theme="white"] .white-mic-circle:focus-visible,
+html[data-theme="white"] .white-mute-btn:focus-visible,
 html[data-theme="white"] .white-stop-btn:focus-visible {
   outline: 3px solid #1d4ed8;
   outline-offset: 4px;
@@ -4706,6 +4709,60 @@ html[data-theme="white"] .white-mic-subcaption {
   text-align: center;
 }
 
+/* ── Active conversation controls ──────────────────────────────────── */
+html[data-theme="white"] .white-session-controls {
+  display: flex;
+  flex-wrap: wrap;
+  align-items: center;
+  justify-content: center;
+  gap: 10px;
+  max-width: 100%;
+}
+html[data-theme="white"] .white-mute-btn {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  min-height: 44px;
+  padding: 10px 16px;
+  border: 1px solid #cbd5e1;
+  border-radius: 999px;
+  background: #ffffff;
+  color: #1d4ed8;
+  font: inherit;
+  font-size: clamp(14px, 3.4vw, 16px);
+  font-weight: 600;
+  cursor: pointer;
+  transition: background 160ms ease, border-color 160ms ease;
+}
+html[data-theme="white"] .white-mute-btn:hover:not(:disabled) {
+  background: #eff6ff;
+  border-color: #93c5fd;
+}
+html[data-theme="white"] .white-mute-btn.muted {
+  background: #fffbeb;
+  border-color: #fcd34d;
+  color: #92400e;
+}
+html[data-theme="white"] .white-mute-btn.muted:hover:not(:disabled) {
+  background: #fef3c7;
+}
+html[data-theme="white"] .white-mute-btn:disabled {
+  cursor: default;
+}
+html[data-theme="white"] .white-mute-btn svg {
+  flex: none;
+  width: 18px;
+  height: 18px;
+}
+html[data-theme="white"] .white-mute-btn .mic-off,
+html[data-theme="white"] .white-mute-btn.muted .mic-on {
+  display: none;
+}
+html[data-theme="white"] .white-mute-btn.muted .mic-off {
+  display: block;
+}
+
 /* ── "Detener" pill ─────────────────────────────────────────────────── */
 html[data-theme="white"] .white-stop-btn {
   display: inline-flex;