Generate comprehensive GitHub Copilot instructions with validated commands and timings

[Copilot]

Creates a comprehensive .github/copilot-instructions.md file that provides GitHub Copilot coding agents with detailed instructions for working effectively in the django-tree-queries codebase.

Key Features

Validated Commands and Timings: All commands have been tested and include accurate timing expectations:

• Admin tests: 4.19 seconds (12 tests)
• Core query tests: 0.52 seconds (55 tests)
• Python linting (ruff): 0.02 seconds
• Django admin server startup: ~5 seconds

Comprehensive Coverage:

• Repository setup and installation (core, admin, and test dependencies)
• Build and test workflows (both tox and direct pytest approaches)
• Code quality tools (ruff, biome, pre-commit hooks)
• Manual validation scenarios for Django admin interface
• Tree query examples and database configurations
• Critical limitations and performance gotchas

Safety-First Approach: Includes explicit "NEVER CANCEL" warnings with specific timeout recommendations for long-running operations like the full tox test suite (20-45 minutes).

Practical Examples: Working code snippets for common tasks like tree operations, admin configuration, and validation workflows that agents can immediately use.

The instructions follow an imperative tone ("Run this command", "Do not do this") and prioritize actionable information that will save agents time and prevent common mistakes when working with this Django tree queries package.

Fixes #97.

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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.