replace excessive toasts with aria-live announcer

Remove redundant success/info toasts (logout, upload loaded, no results).
Keep only error toasts for critical feedback.
Add AriaLiveAnnouncer component for screen reader accessibility.

src/App.tsx

···
 import Firefly from "./components/Firefly";
 import NotificationContainer from "./components/common/NotificationContainer";
 import ErrorBoundary from "./components/common/ErrorBoundary";
+import AriaLiveAnnouncer from "./components/common/AriaLiveAnnouncer";
 import { SearchResultSkeleton } from "./components/common/LoadingSkeleton";
 import { DEFAULT_SETTINGS } from "./types/settings";
 import type { UserSettings, SearchResult } from "./types";
···
     logout,
   } = useAuth();
 
-  // Notifications hook (replaces alerts)
-  const { notifications, removeNotification, success, error, info } =
-    useNotifications();
+  // Notifications hook (only for errors now)
+  const { notifications, removeNotification, error } = useNotifications();
+
+  // Aria-live announcements for non-error feedback (invisible, screen-reader only)
+  const [ariaAnnouncement, setAriaAnnouncement] = useState("");
 
   // Theme hook
   const { isDark, reducedMotion, toggleTheme, toggleMotion } = useTheme();
···
           setSearchResults([]);
           setCurrentPlatform("tiktok");
           setCurrentStep("home");
-          info("No previous results found.");
+          // No visual feedback needed - empty state will show in UI
+          setAriaAnnouncement("No previous results found.");
           return;
         }
 
···
 
         setSearchResults(loadedResults);
         setCurrentStep("results");
-        success(`Loaded ${loadedResults.length} results from previous upload`);
+        // Announce to screen readers only - visual feedback is navigation to results page
+        setAriaAnnouncement(
+          `Loaded ${loadedResults.length} results from previous upload`,
+        );
       } catch (err) {
         console.error("Failed to load upload:", err);
         error("Failed to load previous upload. Please try again.");
         setCurrentStep("home");
       }
     },
-    [setStatusMessage, setCurrentStep, setSearchResults, info, error, success],
+    [setStatusMessage, setCurrentStep, setSearchResults, setAriaAnnouncement, error],
   );
 
   // Login handler
···
       setSearchResults([]);
       setCurrentPlatform("tiktok");
       setSavedUploads(new Set());
-      success("Logged out successfully");
+      // No visual feedback needed - user sees login page
+      setAriaAnnouncement("Logged out successfully");
     } catch (err) {
       error("Failed to logout. Please try again.");
     }
-  }, [logout, setSearchResults, success, error]);
+  }, [logout, setSearchResults, setAriaAnnouncement, error]);
 
   return (
     <ErrorBoundary>
       <div className="min-h-screen relative overflow-hidden">
-        {/* Notification Container */}
+        {/* Notification Container - errors only */}
         <NotificationContainer
           notifications={notifications}
           onRemove={removeNotification}
         />
+
+        {/* Invisible announcer for screen readers - non-error feedback */}
+        <AriaLiveAnnouncer message={ariaAnnouncement} politeness="polite" />
+
+        {/* Status message for screen readers - loading/progress updates */}
+        <AriaLiveAnnouncer message={statusMessage} politeness="polite" />
 
         {/* Firefly particles - only render if motion not reduced */}
         {!reducedMotion && (
···
             ))}
           </div>
         )}
-
-        {/* Status message for screen readers */}
-        <div
-          role="status"
-          aria-live="polite"
-          aria-atomic="true"
-          className="sr-only"
-        >
-          {statusMessage}
-        </div>
 
         {/* Skip to main content link */}
         <a

src/components/common/AriaLiveAnnouncer.tsx

···
+import React, { useEffect, useState } from "react";
+
+interface AriaLiveAnnouncerProps {
+  message: string;
+  politeness?: "polite" | "assertive";
+  clearAfter?: number;
+}
+
+/**
+ * Invisible component that announces messages to screen readers
+ * without displaying visual toasts
+ */
+const AriaLiveAnnouncer: React.FC<AriaLiveAnnouncerProps> = ({
+  message,
+  politeness = "polite",
+  clearAfter = 5000,
+}) => {
+  const [announcement, setAnnouncement] = useState("");
+
+  useEffect(() => {
+    if (message) {
+      // Set the message to trigger screen reader announcement
+      setAnnouncement(message);
+
+      // Clear after specified time to allow new announcements
+      if (clearAfter > 0) {
+        const timer = setTimeout(() => setAnnouncement(""), clearAfter);
+        return () => clearTimeout(timer);
+      }
+    }
+  }, [message, clearAfter]);
+
+  return (
+    <div
+      role="status"
+      aria-live={politeness}
+      aria-atomic="true"
+      className="sr-only"
+    >
+      {announcement}
+    </div>
+  );
+};
+
+export default AriaLiveAnnouncer;