feat: add Ivy demo for Cysharp.ZString

[MedhatZ]

Summary

This PR adds a new Ivy demo application showcasing the usage of Cysharp.ZString.

Features

• Demonstrates ZString.Concat, ZString.Format, and ZString.Join
• Demonstrates usage of ZString.CreateStringBuilder()
• Demonstrates ZString.PrepareUtf16<>

Structure

The example is located in the zstring/ folder and includes:

• HelloApp.cs with interactive Ivy UI buttons
• README.md with instructions
• assets/screenshot.png as a visual reference

Screenshot

[Copilot]

Pull Request Overview

This PR adds a new Ivy demo application that showcases the usage of Cysharp.ZString library for high-performance string operations in .NET.

• Creates a complete demo project with interactive UI buttons demonstrating ZString features
• Implements examples for string concatenation, formatting, joining, StringBuilder usage, and prepared format templates
• Provides Docker configuration and project setup files for easy deployment and development

Reviewed Changes

Copilot reviewed 9 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
zstring/Zstring.sln	Visual Studio solution file for the demo project
zstring/Zstring.csproj	Project file with dependencies on Ivy and ZString packages
zstring/README.md	Documentation with feature overview and run instructions
zstring/Program.cs	Application entry point configuring Ivy server with Chrome UI
zstring/GlobalUsings.cs	Global using statements for Ivy framework namespaces
zstring/Dockerfile	Docker configuration for containerized deployment
zstring/Apps/HelloApp.cs	Main demo app with interactive ZString examples
zstring/.gitignore	Git ignore file for build artifacts and IDE files
zstring/.dockerignore	Docker ignore file excluding unnecessary files from build context

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[MedhatZ]

I've addressed the review feedback:

• Replaced Arabic comments with English.
• Updated Dockerfile to remove /p:UseAppHost=true.

Please let me know if any further changes are needed.

[rorychatt]

It is hard to understand what the library does.

My suggestion is to include also what is happening.

i.e. what strings we concatenate, what we build together, what was formatted

[rorychatt]

[MedhatZ]

I've updated the demo based on the feedback:

• Added explicit inputs and outputs in the UI for Concat, Format, Join, StringBuilder, and Prepared Format.
• Updated README.md to document inputs/outputs with examples.
• Added a new screenshot (assets/screenshot.png) showing the results.

Please review and let me know if there’s anything else to adjust.