Add comprehensive GitHub Copilot instructions for python-webflow-exporter

[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 python-webflow-exporter codebase.

What's included

The instructions cover all essential aspects of development:

🔧 Build and Environment Setup

• Python 3.10+ requirements and dependency installation
• Complete build process with validated timing measurements
• Known network limitations and workarounds

✅ Validation and Testing

• Manual validation scenarios for CLI functionality
• Pre-commit linting requirements (must achieve 10.0/10 pylint score)
• Error handling verification steps

⚡ Performance and Timing

• All commands measured with appropriate timeout recommendations
• Explicit "NEVER CANCEL" warnings for long-running operations
• pip install -r requirements.txt: ~10 seconds
• pylint webexp: ~4 seconds (critical for CI)

🚨 Critical Known Limitations

• Standard installation methods (pip install -e ., python -m build) frequently fail due to network timeouts when accessing PyPI
• This appears to be an environment limitation, not a code issue
• Comprehensive workarounds provided for development

📋 Repository Navigation

• Complete directory structure overview
• Key files to monitor after changes
• CI/CD pipeline information and requirements

Validation Process

Every command and instruction was thoroughly tested:

• ✅ Dependency installation validated (8.5 seconds)
• ✅ Linting process confirmed working (3.7 seconds, perfect score)
• ✅ CLI help/version commands tested (0.2 seconds each)
• ✅ Build limitations documented with attempted workarounds
• ✅ Network timeout issues reproduced and documented

The instructions follow the imperative tone requirement ("Run this command", "Do not do this") and provide exhaustive coverage of the development workflow while honestly documenting limitations encountered during validation.

Fixes #9.

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:

• google.com
  • Triggering command: python /tmp/test_webexp.py --url REDACTED --output test_out (dns block)
• invalid-domain-that-does-not-exist.com
  • Triggering command: python -m webexp.cli --url REDACTED --output test_out (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)

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[Copilot]

Pull Request Overview

This PR adds comprehensive GitHub Copilot instructions to improve development workflow and provide detailed guidance for working with the python-webflow-exporter codebase. The instructions include build setup, validation processes, and troubleshooting for known network limitations.

• Comprehensive development workflow documentation with timing measurements and timeout recommendations
• Manual validation scenarios and pre-commit requirements including mandatory 10.0/10 pylint score
• Detailed troubleshooting section documenting known network timeout issues with PyPI access

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