allow manual connection retry during backoff

src/App.svelte

@@ -116,6 +116,7 @@
   let authBusy = false;
   let connectionNotice = '';
   let connectionCheckRunning = false;
+  let connectionCheckGeneration = 0;
   let realtimeState = 'DISCONNECTED';
   let realtimeSocket: WebSocket | undefined;
   let activityEvents: Array<{ event_id: string; event_type: string; occurred_at: string }> = [];
@@ -277,7 +278,7 @@
   }
 
   async function checkServer() {
-    if (connectionCheckRunning) return;
+    const generation = ++connectionCheckGeneration;
     connectionCheckRunning = true;
     connectionState = 'CONNECTING';
     let attempt = 0;
@@ -290,6 +291,7 @@
       } else {
         connectionNotice = 'Connecting to server';
       }
+      if (generation !== connectionCheckGeneration) return;
       try {
         const response = await fetch(`${serverAddress}/api/v1/server/info`);
         if (!response.ok) throw new Error(`HTTP ${response.status}`);