docs: consolidate Copilot instructions and fix workflow trigger

[Copilot]

Enhanced .github/copilot-instructions.md for better Copilot agent context while maintaining AGENTS.md as the comprehensive source of truth.

Changes

• .github/copilot-instructions.md: Added project overview, expanded commands, key conventions, and important files section. Provides self-contained context for quick reference while linking to AGENTS.md for full details.

• .github/workflows/copilot-setup-steps.yaml: Fixed trigger paths from .yml to .yaml to match actual filename.

Structure

• .github/copilot-instructions.md (34 lines): Actionable quick reference
• AGENTS.md (140 lines): Comprehensive documentation (unchanged)
• Both files cross-reference each other

• By submitting this pull request, I assign the copyright of my contribution to The igraph development team.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

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

• gh.io
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)
  • Triggering command: /usr/bin/curl curl -L REDACTED (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 the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

Consolidate with existing instructions. In particular, ensure AGENTS.md remains the source of truth.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ✨ Set up Copilot instructions #2535

---

💡 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.

[Copilot]

Pull request overview

This pull request consolidates GitHub Copilot instructions and fixes a workflow trigger path. It enhances .github/copilot-instructions.md to provide better self-contained context for Copilot agents while maintaining AGENTS.md as the comprehensive source of truth.

Changes:

• Enhanced .github/copilot-instructions.md with project overview, expanded commands, key conventions, and important files sections
• Fixed workflow trigger paths in .github/workflows/copilot-setup-steps.yaml from .yml to .yaml to match actual filename

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
.github/workflows/copilot-setup-steps.yaml	Corrects trigger paths to match actual .yaml file extension
.github/copilot-instructions.md	Expands quick reference guide with project overview, additional commands, conventions, and important file information while cross-referencing AGENTS.md

[Copilot]

The test commands should include the reporter = "check" parameter to be consistent with AGENTS.md. The source of truth (AGENTS.md lines 39-40, 139) consistently specifies testthat::test_local(reporter = "check") for running tests. This parameter ensures consistent output formatting across different test runs.