This PR adds comprehensive GitHub Copilot instructions for Flutter and Dart development, following the formatting and conventions of existing instruction files in the repository.

New File Added

• instructions/flutter-dart.md - Complete Flutter and Dart development guidelines (594 lines)

What's Included

Core Development Guidelines

• Error Handling: Clear messages, user feedback, error boundaries, logging, error reporting, TODO comments, input validation, edge case handling, and recovery mechanisms
• General Guidelines: Dart language best practices, null-safety, code style, formatting, and const constructors
• Flutter Best Practices: Widget structure, state management, responsive design, performance optimization, error handling, dependencies, security, and internationalization

Project Organization & Code Quality

• File & Project Structure: Organized by models, screens, widgets with clean architecture patterns
• Code Suggestions: Context-aware recommendations, complete snippets, proper imports, modern Dart 3.0+ features, Material Design 3 integration
• Testing & Debugging: Unit, widget, integration tests; debugPrint, logging, analysis tools

Development Workflow

• CI/CD and Workflow: GitHub Actions, semantic versioning, GitFlow best practices
• Common Patterns: async/await, InheritedWidget, ThemeData, navigation patterns
• Context Awareness: Intent recognition, clarifying questions, library recommendations

Additional Features

• Accessibility: WCAG compliance, semantic labels, screen reader support
• Platform-specific UI: iOS vs Android considerations, adaptive widgets
• Performance: Best practices to avoid outdated patterns and optimize apps

Example Code Samples

The instructions include complete, working code examples for:

• Custom widget creation with proper error handling
• Async data loading with comprehensive error handling
• New screen implementation with state management
• API client usage with timeout and error handling

Format Compliance

• ✅ YAML frontmatter with description and file patterns
• ✅ Proper markdown structure with ## headers and bullet formatting
• ✅ Consistent style matching existing files like blazor.md and angular.md
• ✅ Automatically updated README.md via the update script

The file provides comprehensive guidance for creating maintainable, performant, and user-friendly Flutter applications following modern development practices.

💡 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.