Add XML documentation comments to public and internal types

[bfren]

Summary

This PR adds comprehensive XML documentation comments to all public and internal types throughout the Wrap library, improving code documentation and IDE IntelliSense support.

Key Changes

• Added <summary> XML documentation comments to all partial class definitions across the codebase
• Documented extension method classes with "Extension methods for functional monad operations."
• Documented utility function classes (F, M, R, E) with their specific purposes
• Documented internal constants class (C) and its nested GetSingle class
• Documented monad types (Maybe, Result) and related structures (Failure)
• Documented model binder helpers for ASP.NET Core MVC integration
• Ensured consistent documentation across all partial class files

Implementation Details

• All documentation follows the standard XML documentation format (/// <summary>)
• Documentation is placed immediately before class declarations
• Descriptions are concise and accurately reflect the purpose of each type
• Covers all namespaces: Wrap, Wrap.Extensions, Wrap.Mvc, Wrap.Json, Wrap.Linq, Wrap.Testing
• No functional code changes; purely additive documentation improvements

https://claude.ai/code/session_01U8BXjRoXM1LnuNVaKgJEoK