docs: Add GitHub Copilot instructions

[Copilot]

This PR adds a comprehensive .github/copilot-instructions.md file that provides GitHub Copilot coding agents with detailed instructions for working effectively in the eslint-github-bot repository.

What's included

The instructions provide exhaustively validated guidance covering:

Repository Setup & Build Process:

• Complete bootstrap commands (npm install, dependency setup)
• Environment configuration with .env file requirements
• Build and test workflows with precise timing expectations

Plugin Architecture Documentation:

• Detailed coverage of all 6 plugins (auto-assign, commit-message, needs-info, recurring-issues, release-monitor, wip)
• Plugin development workflow and file structure
• Common patterns for Probot event handlers

Validated Commands & Timing:

• npm test: ~3 seconds (284 tests, 98.31% coverage)
• npm run lint: ~1.5 seconds
• npm start: immediate startup with health check validation
• Specific timeout recommendations with "NEVER CANCEL" warnings

Manual Validation Requirements:

• Server functionality testing via /ping endpoint
• Individual plugin test execution
• Complete development workflow validation steps

Troubleshooting & Production Notes:

• Node.js version compatibility (22.x preferred, works on 20.x)
• Deployment details for Dokku/github-bot.eslint.org
• Common issues and resolution steps

All commands and procedures have been thoroughly tested and validated to ensure the instructions work reliably for any developer or AI agent working with this codebase for the first time.

Fixes #227.

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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.

[eslint-github-bot]

Hi @Copilot!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here

[linux-foundation-easycla]

• ❌ - login: @Copilot / name: copilot-swe-agent[bot] . The commit (f1cbe67, 644a886) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[eslint-github-bot]

Hi @Copilot!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here

[eslint-github-bot]

Hi @Copilot!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here

[eslint-github-bot]

Hi @Copilot!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here

[eslint-github-bot]

Hi @Copilot!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here

[eslint-github-bot]

Hi @Copilot!, thanks for the Pull Request

The pull request title isn't properly formatted. We ask that you update the pull request title to match this format, as we use it to generate changelogs and automate releases.

• The commit message tag wasn't recognized. Did you mean "docs", "fix", or "feat"?
• There should be a space following the initial tag and colon, for example 'feat: Message'.
• The first letter of the tag should be in lowercase

To Fix: You can fix this problem by clicking 'Edit' next to the pull request title at the top of this page.

Read more about contributing to ESLint here