fix alerts reconnect backoff and clipboard availability checks

ui/src/App.tsx

@@ -207,6 +207,7 @@ export function App() {
         // Only a connection that stayed up proves the stream is healthy; an
         // accept-then-close server must not pin us to the first backoff step.
         if (openedAt && Date.now() - openedAt > 10_000) attempt = 0;
+        openedAt = 0;
         // Browsers never reconnect a WebSocket on their own.
         const delay =
           Math.min(30_000, 1000 * 2 ** attempt) + Math.random() * 1000;

ui/src/pages/terminal/useXterm.ts

@@ -172,6 +172,10 @@ export function useXterm({ pageRef, hostRef }: Options) {
       toast.info("Nothing to copy");
       return;
     }
+    if (!navigator.clipboard) {
+      toast.error("Clipboard access requires HTTPS or localhost");
+      return;
+    }
     try {
       await navigator.clipboard.writeText(text);
       toast.success(
@@ -184,6 +188,10 @@ export function useXterm({ pageRef, hostRef }: Options) {
     }
   }, []);
   const paste = useCallback(async (writeData: (data: string) => void) => {
+    if (!navigator.clipboard) {
+      toast.error("Clipboard access requires HTTPS or localhost");
+      return;
+    }
     try {
       const text = await navigator.clipboard.readText();
       if (text) writeData(text);