Create comprehensive GitHub Copilot instructions for PostgreSQL cookbook development

[Copilot]

This PR creates a comprehensive .github/copilot-instructions.md file that provides detailed guidance for GitHub Copilot coding agents working with the PostgreSQL Chef cookbook. The instructions were created through exhaustive validation of commands and development workflows in the actual repository environment.

What's Included

The instructions provide validated guidance for:

Environment Setup

• Ruby development environment configuration
• Required gem installation (cookstyle, deepsort, inifile)
• PATH configuration for user-installed gems

Development Workflows

• Code linting with Cookstyle (validated at ~2-3 seconds for 52 files)
• Ruby syntax validation for all cookbook files
• Pre-commit validation procedures

Repository Navigation

• Key directory structure (/resources/, /libraries/, /test/, /documentation/)
• Important configuration files (metadata.rb, kitchen.yml, .rubocop.yml)
• Resource usage patterns from test examples

Limitations Documentation

• Network access restrictions preventing berks install and Test Kitchen execution
• RSpec/ChefSpec gem conflicts preventing unit test execution
• Alternative validation approaches for sandbox environments

Performance Expectations

• Measured timing for common operations
• CI/CD pipeline expectations and timeout guidance

Validation Process

Every command and workflow in the instructions was validated by:

• Installing and testing all required Ruby gems
• Running Cookstyle linting across the entire codebase
• Syntax-checking all Ruby files in the cookbook
• Testing repository exploration and navigation commands
• Documenting actual performance timings

The instructions follow the imperative tone requirement ("Run this command", "Do not do this") and provide explicit fallback guidance when sandbox limitations prevent full functionality testing.

Fixes #798.

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:

• supermarket.chef.io
  • Triggering command: /usr/bin/ruby3.2 /home/REDACTED/.local/share/gem/ruby/3.2.0/bin/berks install (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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[github-actions]

Slowest examples

Top 10 slowest examples (0.01 seconds, 49.2% of total time)

Example	Description	Time in seconds
spec/libraries/helpers_spec.rb:19	PostgreSQL::Cookbook::Helpers#data_dir(version) with rhel family and Postgres 11 from repo returns the correct path	0.01226
spec/libraries/helpers_spec.rb:27	PostgreSQL::Cookbook::Helpers#data_dir(version) with rhel family and Postgres 11 from os returns the correct path	0.00046
spec/libraries/helpers_spec.rb:65	PostgreSQL::Cookbook::Helpers#conf_dir(version) with rhel family and Postgres 11 from os returns the correct path	0.00042
spec/libraries/helpers_spec.rb:103	PostgreSQL::Cookbook::Helpers#default_platform_service_name(version) with rhel family and Postgres 12 from os returns the correct service name	0.00037
spec/libraries/helpers_spec.rb:111	PostgreSQL::Cookbook::Helpers#default_platform_service_name(version) with debian family and Postgres 15 from repo returns the correct service name	0.00036
spec/libraries/helpers_spec.rb:73	PostgreSQL::Cookbook::Helpers#conf_dir(version) with debian family and Postgres 11 from repo returns the correct path	0.00036
spec/libraries/helpers_spec.rb:95	PostgreSQL::Cookbook::Helpers#default_platform_service_name(version) with rhel family and Postgres 13 from repo returns the correct service name	0.00036
spec/libraries/helpers_spec.rb:35	PostgreSQL::Cookbook::Helpers#data_dir(version) with debian family and Postgres 11 from repo returns the correct path	0.00036
spec/libraries/helpers_spec.rb:81	PostgreSQL::Cookbook::Helpers#conf_dir(version) with debian family and Postgres 14 from os returns the correct path	0.00035
spec/libraries/helpers_spec.rb:103	PostgreSQL::Cookbook::Helpers#default_platform_service_name(version) with rhel family and Postgres 13 from os returns the correct service name	0.00035