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/core/hooks/useAppInitialization.ts

@@ -0,0 +1,10 @@
+/**
+ * App initialization hook
+ * Core version: no initialization needed
+ *
+ * This hook is called once when the app starts to allow different builds
+ * to perform initialization tasks that require access to contexts like FileContext.
+ */
+export function useAppInitialization(): void {
+  // Core version has no initialization
+}