Add Copilot coding agent instructions

.github/copilot-instructions.md

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+# Copilot Instructions for Android Syntax Highlighter
+
+## Repository Summary
+
+This is an Android library project that demonstrates how to integrate web-based syntax highlighting (PrismJS and highlight.js) into Android applications using WebView. It supports Android Legacy Views, Fragments, and Jetpack Compose. The project is **not** a published library—it's a reference implementation for developers to copy and adapt.
+
+## Project Overview
+
+- **Language**: Kotlin (primary), Java (minimal)
+- **Build System**: Gradle 8.11.1 with Android Gradle Plugin 8.5.2
+- **Min SDK**: 29 (Android 10), Target SDK: 35 (Android 15)
+- **Java Version**: 17 (required)
+- **Kotlin Version**: 2.0.21
+- **Architecture**: Multi-module Gradle project with two modules
+
+## Build Commands
+
+**Always use the Gradle wrapper** (`./gradlew`) for builds. Do not use system Gradle.
+
+| Task | Command | Description |
+|------|---------|-------------|
+| Build All | `./gradlew build` | Compiles both modules, runs unit tests, generates APK |
+| Clean Build | `./gradlew clean build` | Clean and rebuild from scratch |
+| Unit Tests | `./gradlew test` | Run unit tests only |
+| Lint | `./gradlew lint` | Run Android Lint checks |
+| Assemble Debug | `./gradlew assembleDebug` | Build debug APK only |
+| Assemble Release | `./gradlew assembleRelease` | Build release APK only |
+
+**Build time**: First build takes 2-3 minutes (downloads Gradle and dependencies). Subsequent builds are faster with configuration cache enabled.
+
+## Project Structure
+
+```
+android-syntax-highlighter/
+├── highlighter/           # Library module (reusable syntax highlighting components)
+│   ├── build.gradle       # Library build config
+│   └── src/main/
+│       ├── assets/www/    # PrismJS & highlight.js files (prism.js, prism.css, etc.)
+│       └── java/dev/hossain/ynaash/
+│           ├── compose/   # SyntaxHighlighterComposable.kt (Jetpack Compose)
+│           ├── prismjs/   # PrismJS implementation (Fragment, WebView, Template)
+│           ├── highlightjs/ # highlight.js implementation
+│           └── webclient/ # WebView client utilities
+├── example/               # Demo application module
+│   ├── build.gradle       # App build config
+│   └── src/main/java/dev/hossain/ynaash/example/
+│       ├── SampleApp.kt   # Application class
+│       └── ui/            # Demo activities (MainActivity, PrismJsDemoActivity, etc.)
+├── build.gradle           # Root project build file (defines shared versions)
+├── settings.gradle        # Module includes
+├── gradle.properties      # Build configuration
+└── gradle/wrapper/        # Gradle wrapper (8.11.1)
+```
+
+## Key Source Files
+
+| File | Purpose |
+|------|---------|
+| `highlighter/src/main/java/dev/hossain/ynaash/prismjs/SyntaxHighlighterWebView.kt` | Main custom WebView for PrismJS |
+| `highlighter/src/main/java/dev/hossain/ynaash/prismjs/SyntaxHighlighterFragment.kt` | Fragment-based implementation |
+| `highlighter/src/main/java/dev/hossain/ynaash/prismjs/PrismJsHtmlTemplate.kt` | HTML template function |
+| `highlighter/src/main/java/dev/hossain/ynaash/compose/SyntaxHighlighterComposable.kt` | Jetpack Compose wrapper |
+| `example/src/main/java/dev/hossain/ynaash/example/ui/MainActivity.kt` | Demo app entry point |
+
+## Configuration Files
+
+| File | Purpose |
+|------|---------|
+| `build.gradle` (root) | Defines Kotlin version, Android Gradle Plugin, shared dependency versions |
+| `gradle.properties` | JVM args, AndroidX settings, configuration cache enabled |
+| `settings.gradle` | Defines modules: `:highlighter` and `:example` |
+| `.github/workflows/android.yml` | CI workflow (build on push/PR to main/develop) |
+
+## CI Workflow
+
+The GitHub Actions workflow (`.github/workflows/android.yml`) runs on:
+- Push to `main` branch
+- Pull requests to `main` or `develop` branches
+
+**CI Steps**:
+1. Checkout code
+2. Setup Java 17 (Zulu distribution)
+3. Setup Gradle
+4. Run `./gradlew build`
+
+**To validate changes locally before pushing**, run: `./gradlew build`
+
+## Dependencies (defined in root build.gradle `ext` block)
+
+All version numbers are centralized in the root `build.gradle` file under the `ext` block (not using version catalogs):
+- `appCompatVersion = '1.7.0'`
+- `coreKtxVersion = '1.15.0'`
+- `composeBomVersion = '2024.12.01'`
+- `junitVersion = '4.13.2'`
+- `espressoCoreVersion = '3.6.1'`
+- `timberLibraryVersion = '5.0.1'`
+
+## Testing
+
+- **Unit tests**: Located in `*/src/test/java/` directories
+- **Instrumented tests**: Located in `*/src/androidTest/java/` directories
+- Tests are minimal (example placeholder tests exist)
+- Run unit tests: `./gradlew test`
+- Run instrumented tests: `./gradlew connectedAndroidTest` (requires Android emulator/device)
+
+## Code Style
+
+- Kotlin code style: `official` (set in gradle.properties)
+- No custom linting rules configured
+- Standard Android/Kotlin conventions apply
+
+## Important Notes
+
+1. **JavaScript is enabled** in WebViews (`@SuppressLint("SetJavaScriptEnabled")`) - this is intentional for syntax highlighting functionality.
+
+2. **Web assets location**: All JS/CSS files for syntax highlighting are in `highlighter/src/main/assets/www/`.
+
+3. **No library publication**: This project is not published to Maven. It's reference code to copy.
+
+4. **Compose support**: Uses Compose BOM for version management. The `SyntaxHighlighter` composable wraps the WebView implementation.
+
+5. **Two syntax highlighters**: Both PrismJS (`prismjs/`) and highlight.js (`highlightjs/`) implementations exist. PrismJS is the primary/recommended one.
+
+## Trust These Instructions
+
+These instructions have been validated against the actual repository structure. Only search for additional information if:
+- The build commands fail with unexpected errors
+- Files mentioned do not exist
+- You need details about a specific implementation not covered here