fix(push): include underlying error text in subscribe failure toast

Sellers running from an installed PWA still hit failures inside subscribe
(iOS 16.4+ PWA has its own quirks even when standalone), and a generic
"لطفاً چند لحظه بعد دوباره تلاش کنید" doesn't tell whoever is helping
them what actually broke. The catch handler now surfaces the underlying
Error.message (e.g. "timeout: pushManager.subscribe", "NotAllowedError")
in the toast description so field debugging works over screenshots.

Co-Authored-By: Claude <noreply@anthropic.com>

app/hooks/usePushNotifications.ts

@@ -198,10 +198,13 @@ export function usePushNotifications() {
       return ok;
     } catch (e) {
       console.error("Push subscribe failed:", e);
-      // Anything unexpected — surface it so the seller knows to retry.
+      // Include the step name / error text in the toast so field debugging
+      // doesn't need browser console access — sellers can read out what
+      // failed to whoever's helping them.
+      const detail = e instanceof Error ? e.message : String(e);
       toast({
         title: "فعال‌سازی اعلان با خطا مواجه شد",
-        description: "لطفاً چند لحظه بعد دوباره تلاش کنید.",
+        description: `${detail || "خطای ناشناخته"}. لطفاً چند لحظه بعد دوباره تلاش کنید.`,
         variant: "destructive",
       });
       return false;