Configure comprehensive GitHub Copilot instructions

[Copilot]

Establishes comprehensive coding agent instructions following GitHub's best practices for repository context and conventions.

Changes

Enhanced .github/copilot-instructions.md (550 → 1,100+ lines):

• Quick Reference - Tech stack, commands, 10 learning modules overview
• Accurate Architecture - Features-based structure (src/features/, src/shared/) vs outdated sections-based docs
• Complete Module Coverage - Added React, TypeScript, System Design (previously undocumented)
• Shared Infrastructure - Context providers, services, custom hooks, reusable components
• Testing Patterns - Vitest + React Testing Library setup with examples
• Development Workflow - Verified npm scripts, pre-commit checklist, feature addition guide
• Code Quality - ESLint/Prettier/TypeScript strict mode standards
• Common Pitfalls - Light mode only (no dark: classes), proper directory structure
• Module-Specific Guidelines - Visualization patterns, color schemes, metaphors for all 10 modules

Structure Example

// Adding a new module follows documented pattern
src/features/[module]/
├── components/
│   ├── sections/         # Educational content
│   └── visualizations/   # Interactive 2D/3D models
└── index.tsx             # Lazy-loaded page entry

// With theme in src/utils/theme.ts
colors: {
  module: {
    primary: 'blue',
    gradient: 'from-blue-50 via-white to-indigo-50',
    // ...
  }
}

Copilot now has complete context on project structure, conventions, and patterns for code generation and review tasks.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ✨ Set up Copilot instructions #7

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