Tidy Tauri code and enable "Open file in Stirling PDF" (#4836)

# Description of Changes
Tidy Tauri code and enable "Open file in Stirling PDF"

frontend/src/desktop/components/AppProviders.tsx

@@ -0,0 +1,20 @@
+import { ReactNode } from "react";
+import { AppProviders as ProprietaryAppProviders } from "@proprietary/components/AppProviders";
+
+/**
+ * Desktop application providers
+ * Wraps proprietary providers and adds desktop-specific configuration
+ * - Enables retry logic for app config (needed for Tauri mode when backend is starting)
+ */
+export function AppProviders({ children }: { children: ReactNode }) {
+  return (
+    <ProprietaryAppProviders
+      appConfigRetryOptions={{
+        maxRetries: 5,
+        initialDelay: 1000, // 1 second, with exponential backoff
+      }}
+    >
+      {children}
+    </ProprietaryAppProviders>
+  );
+}