fix(api): Fix S3 backup path-style configuration and improve UX.

- Fix critical S3 client configuration bug for path-style addressing
- Add toast notifications for better user feedback on S3 config operations
- Set up Toaster component in root layout for app-wide notifications
- Clean up unused imports in test files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

frontend/src/components/S3BackupConfigDrawer.tsx

@@ -1,6 +1,7 @@
 import { useState, useEffect } from "react";
 import { useMutation, useQueryClient } from "@tanstack/react-query";
 import { Cloud, TestTube } from "lucide-react";
+import { toast } from "sonner";
 import { apiClient } from "../lib/api";
 import { Button } from "./ui/button";
 import { Input } from "./ui/input";
@@ -55,9 +56,12 @@ export default function S3BackupConfigDrawer({
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ["backupSettings"] });
       setOpen(false);
+      toast.success("S3 backup configuration saved successfully");
     },
-    onError: (error) => {
+    onError: (error: any) => {
       console.error("Failed to update S3 backup configuration:", error);
+      const message = error?.response?.data?.detail || "Failed to save S3 configuration. Please check your settings and try again.";
+      toast.error(message);
     },
   });
 
@@ -69,9 +73,12 @@ export default function S3BackupConfigDrawer({
       }),
     onSuccess: () => {
       console.log("S3 connection test successful");
+      toast.success("S3 connection test successful! Your configuration is working correctly.");
     },
-    onError: (error) => {
+    onError: (error: any) => {
       console.error("Failed to test S3 connection:", error);
+      const message = error?.response?.data?.detail || "S3 connection test failed. Please verify your credentials and settings.";
+      toast.error(message);
     },
   });
 
@@ -245,4 +252,4 @@ export default function S3BackupConfigDrawer({
       </DrawerContent>
     </Drawer>
   );
-}
+}

frontend/src/routes/__root.tsx

@@ -5,6 +5,7 @@ import { PWAInstallPrompt, PWAUpdatePrompt } from "../components/PWAPrompts";
 import { usePWA } from "../hooks/usePWA";
 import { useVersionCheck } from "../hooks/useVersionCheck";
 import { SidebarInset, SidebarProvider } from "../components/ui/sidebar";
+import { Toaster } from "../components/ui/sonner";
 
 function RootLayout() {
   const { updateAvailable, updateSW, forceReload } = usePWA();
@@ -48,6 +49,9 @@ function RootLayout() {
         updateAvailable={updateAvailable}
         onUpdate={handlePWAUpdate}
       />
+
+      {/* Toast Notifications */}
+      <Toaster />
     </SidebarProvider>
   );
 }