Add comprehensive GitHub Copilot development instructions for LLM Canvas

[Copilot]

This PR adds comprehensive development instructions in .github/copilot-instructions.md to help GitHub Copilot coding agents work effectively in the LLM Canvas codebase. The instructions provide exhaustive guidance for developers working with a fresh clone of the repository.

Key Features Added

Complete Build & Test Workflow

• Detailed setup instructions for Python (uv) and Node.js environments
• All commands validated with actual execution times and timeout recommendations
• Explicit "NEVER CANCEL" warnings for longer operations (e.g., type checking takes 10s, frontend build takes 7s)

Pre-commit Validation Requirements

• Comprehensive linting, formatting, and type checking commands that match the CI pipeline
• Manual testing scenarios for server health, example execution, and web interface validation
• Specific curl commands and expected outputs for verification

Development Workflow Guidelines

• Step-by-step setup process from dependency installation to running examples
• Clear separation between local development and CI/CD processes
• Frontend development server setup and integration testing procedures

Repository Structure Documentation

• Detailed explanation of core components and their relationships
• Build artifacts and generated files with proper .gitignore management
• Time expectations for all common operations to set appropriate timeouts

Troubleshooting Guide

• Common issues and their solutions (server startup, example failures, build issues)
• Debug procedures for frontend/backend integration problems
• Dependency management and environment setup fixes

Validation Performed

All instructions were thoroughly tested including:

• ✅ Python dependency installation (4 seconds with uv)
• ✅ Frontend dependency installation (15 seconds with npm)
• ✅ Complete build pipeline (frontend: 7s, Python package: 2s)
• ✅ Linting and type checking (ruff: 0.1s, mypy: 10s)
• ✅ Server startup and example execution
• ✅ Web interface accessibility and API health checks
• ✅ OpenAPI schema and client generation (3 seconds total)

The instructions follow an imperative tone as requested and start with a firm directive to follow these instructions first before searching for additional context.

Fixes #27.

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:

• astral.sh
  • Triggering command: curl -LsSf 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)

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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.