Add remote stream relay feature: relay remote DJ streams to listeners

- Server-side: Added remote URL support in ffmpeg transcoder
- UI: Added relay controls in streaming panel with URL input
- Client: Added start/stop relay functions with socket communication
- Listener: Shows remote relay status in stream indicator

style.css

@@ -2320,6 +2320,75 @@ input[type=range] {
     opacity: 0.7;
 }
 
+/* Remote Relay Section */
+.remote-relay-section {
+    padding: 15px;
+    background: rgba(0, 0, 0, 0.3);
+    border-radius: 8px;
+    border: 1px solid rgba(0, 243, 255, 0.3);
+}
+
+.remote-relay-section h4 {
+    margin: 0 0 15px 0;
+    color: var(--primary-cyan);
+    font-family: 'Orbitron', sans-serif;
+    font-size: 1rem;
+}
+
+.relay-controls {
+    display: flex;
+    flex-direction: column;
+    gap: 10px;
+}
+
+.relay-url-input {
+    padding: 10px;
+    background: rgba(0, 0, 0, 0.5);
+    border: 1px solid var(--primary-cyan);
+    color: var(--text-main);
+    border-radius: 5px;
+    font-family: 'Rajdhani', monospace;
+    font-size: 0.85rem;
+}
+
+.relay-btn {
+    padding: 12px;
+    background: linear-gradient(145deg, #1a1a1a, #0a0a0a);
+    border: 2px solid var(--primary-cyan);
+    color: var(--primary-cyan);
+    font-family: 'Orbitron', sans-serif;
+    font-size: 0.9rem;
+    font-weight: bold;
+    cursor: pointer;
+    border-radius: 5px;
+    transition: all 0.3s;
+    box-shadow: 0 0 15px rgba(0, 243, 255, 0.2);
+}
+
+.relay-btn:hover {
+    background: linear-gradient(145deg, #2a2a2a, #1a1a1a);
+    box-shadow: 0 0 25px rgba(0, 243, 255, 0.4);
+    transform: translateY(-1px);
+}
+
+.relay-btn.stop {
+    border-color: #ff4444;
+    color: #ff4444;
+    box-shadow: 0 0 15px rgba(255, 68, 68, 0.2);
+}
+
+.relay-btn.stop:hover {
+    background: rgba(255, 68, 68, 0.1);
+    box-shadow: 0 0 25px rgba(255, 68, 68, 0.4);
+}
+
+.relay-status {
+    margin-top: 10px;
+    font-size: 0.85rem;
+    color: var(--text-dim);
+    min-height: 20px;
+}
+
 /* ========== LISTENER MODE ========== */
 
 .listener-mode {