fix: harden PWA install prompt

src/lib/useInstallPrompt.ts

@@ -1,4 +1,4 @@
-import { useEffect, useState } from "react";
+import { useEffect, useRef, useState } from "react";
 
 export type InstallPromptState = "unsupported" | "available" | "ios-instructions" | "installed";
 
@@ -26,6 +26,7 @@ export function useInstallPrompt() {
   });
   const [deferred, setDeferred] = useState<BeforeInstallPromptEvent | null>(null);
   const [dismissed, setDismissed] = useState(false);
+  const installInFlight = useRef(false);
 
   useEffect(() => {
     if (isStandalone()) {
@@ -40,6 +41,7 @@ export function useInstallPrompt() {
     };
     const onInstalled = () => {
       setDeferred(null);
+      setDismissed(false);
       setState("installed");
     };
 
@@ -52,13 +54,21 @@ export function useInstallPrompt() {
   }, []);
 
   const install = async () => {
-    if (!deferred) return;
+    if (!deferred || installInFlight.current) return;
     const event = deferred;
+    installInFlight.current = true;
     setDeferred(null);
-    await event.prompt();
-    const choice = await event.userChoice;
-    if (choice.outcome === "accepted") setState("installed");
-    else setDismissed(true);
+    try {
+      await event.prompt();
+      const choice = await event.userChoice;
+      if (choice.outcome === "accepted") setState("installed");
+      else setDismissed(true);
+    } catch {
+      setDeferred(event);
+      setState("available");
+    } finally {
+      installInFlight.current = false;
+    }
   };
 
   return { state: dismissed ? "unsupported" : state, install, dismiss: () => setDismissed(true) };