Changed GetAllItems to accept a folder UUID instead of InventoryNode, updating all relevant calls. Improved inventory item retrieval logic for outfit management and fixed recursive traversal to use folder UUIDs.
Migrated all serialization and deserialization from Newtonsoft.Json to System.Text.Json across the codebase for improved performance and reduced dependencies. Updated package references and refactored helper method names for consistency (e.g., IsEmpty, NotEmpty, InRange). Also updated NuGet package versions in project files.
