Add .github/copilot-instructions.md for improved Copilot assistance

[Copilot]

This PR adds a comprehensive .github/copilot-instructions.md file to help GitHub Copilot provide more contextual and accurate assistance when working with the Java.Interop repository.

What's Included

The instructions file provides detailed guidance covering:

Project Overview

• Java.Interop as a .NET library providing JNI bindings for C# to Java interoperability
• Key use cases including .NET for Android development and desktop Java integration

Architecture & Core Concepts

• JNI fundamentals with type-safe bindings using JniObjectReference instead of raw IntPtr
• Type system and marshaling between Java and .NET types
• Code generation pipeline from XML API descriptions to C# binding code

Repository Structure

• Core libraries (Java.Interop, Java.Runtime.Environment, etc.)
• Code generation tools (generator, class-parse, jcw-gen)
• Supporting libraries for Maven integration, bytecode analysis, and source processing
• Testing framework and sample projects

Development Guidelines

• Naming conventions (Java* vs Jni* prefixes)
• Memory management patterns for JNI references
• Error handling and exception marshaling
• Threading considerations with JNI environments

Common Development Tasks

• Binding Java libraries using the generator toolchain
• Adding custom type marshalers
• Working with Javadoc conversion
• Performance optimization techniques

Build System & Testing

• Build prerequisites and commands
• Configuration options and local customization
• Testing patterns for unit, integration, and performance tests

This comprehensive guide will enable Copilot to better understand the project context and provide more relevant suggestions for Java interop development tasks.

Fixes #1341.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• 1javsblobprodcus364.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• 7tjvsblobprodcus341.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• c78vsblobprodcus322.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• d0svsblobprodcus381.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• jd4vsblobprodcus366.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• l49vsblobprodcus358.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• uy6vsblobprodcus34.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)
• vb4vsblobprodcus33.vsblob.vsassets.io
  • Triggering command: dotnet build -t:Prepare (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to my firewall allow list

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.