Enhance WebSocket client connection logic and improve event listener management (#3636)

- Updated WebSocketClient to allow connection during CONNECTING state.
- Introduced a flag for reconnection attempts.
- Improved event listener registration to prevent duplicate callbacks.
- Refactored online clients update logic in inbounds.html for better performance and clarity.
- Added CSS styles for subscription link boxes in subpage.html to enhance UI consistency and interactivity.

Co-authored-by: lolka1333 <test123@gmail.com>

web/assets/js/websocket.js

@@ -14,10 +14,12 @@ class WebSocketClient {
   }
 
   connect() {
-    if (this.ws && this.ws.readyState === WebSocket.OPEN) {
+    if (this.ws && (this.ws.readyState === WebSocket.OPEN || this.ws.readyState === WebSocket.CONNECTING)) {
       return;
     }
 
+    this.shouldReconnect = true;
+
     const protocol = window.location.protocol === 'https:' ? 'wss:' : 'ws:';
     // Ensure basePath ends with '/' for proper URL construction
     let basePath = this.basePath || '';
@@ -97,7 +99,10 @@ class WebSocketClient {
     if (!this.listeners.has(event)) {
       this.listeners.set(event, []);
     }
-    this.listeners.get(event).push(callback);
+    const callbacks = this.listeners.get(event);
+    if (!callbacks.includes(callback)) {
+      callbacks.push(callback);
+    }
   }
 
   off(event, callback) {