chore(copilot): scaffold repo instructions (#404)

* Initial plan

* Add GitHub Copilot Chat customization baseline assets and repo-specific instructions

Co-authored-by: wax911 <[email protected]>

* chore(copilot): remove chat modes and prompts; update contributing

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: wax911 <[email protected]>
Co-authored-by: Maxwell Mapako <[email protected]>

Author: Copilot

.github/instructions/context.instructions.md

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+---
+applyTo: **
+description: This file describes the overall architecture and module structure of the android-emojify project.
+---
+
+# Android Emojify Project Overview
+
+Android Emojify is a lightweight Kotlin library that helps you use Emojis in your Android applications. It's a port of [vdurmont/emoji-java](https://github.com/vdurmont/emoji-java) rewritten in Kotlin with Android-specific optimizations.
+
+## Project Structure
+
+The project follows a multi-module architecture organized into distinct layers:
+
+### Core Modules
+- **emojify** - The main library module containing the core emoji functionality
+- **serializer** - Module for emoji data serialization and parsing
+- **contract** - Shared contracts and interfaces
+- **app** - Sample application demonstrating library usage
+
+### Build System
+- **buildSrc** - Contains custom Gradle plugins and build logic
+  - Custom dependency management extensions
+  - Android configuration components
+  - Spotless code formatting setup
+  - Dokka documentation generation
+
+### Key Technologies
+- **Kotlin** - Primary language with coroutines support
+- **Android Gradle Plugin** - For Android-specific build configuration
+- **Room** - For local emoji data storage (if applicable)
+- **Timber** - Logging framework
+- **JUnit + MockK** - Testing framework
+
+### Module Dependencies
+- The `emojify` module is the main library that other applications depend on
+- The `app` module serves as both a sample and testing ground for the library
+- The `serializer` module handles emoji data processing
+- Build modules in `buildSrc` provide shared build logic
+
+### Architecture Principles
+- **Separation of Concerns** - Each module has a specific responsibility
+- **Dependency Inversion** - Higher-level modules don't depend on lower-level modules directly
+- **Testability** - Code is structured to be easily testable with unit and integration tests
+- **Performance** - Optimized for Android runtime with efficient emoji lookups
+
+### Usage Pattern
+The library is designed to be used as a dependency in Android projects, providing easy emoji support through simple APIs. It's already being used in production in the AniTrend application.
+
+### Documentation
+- Main documentation is available at: https://anitrend.github.io/android-emojify/
+- Supported emojis are listed in SUPPORTED.md
+- API documentation is generated using Dokka