chore: add Copilot instructions for repository (#574)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: naorpeled <6171622+naorpeled@users.noreply.github.com>

.github/copilot-instructions.md

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+# Copilot Instructions for Bowser
+
+## Project Overview
+
+Bowser is a small, fast, and rich-API browser/platform/engine detector for both browser and Node.js environments. It's designed to parse User-Agent strings and provide detailed information about browsers, operating systems, platforms, and rendering engines.
+
+## Architecture
+
+### Core Components
+
+- **`src/bowser.js`**: Main entry point and public API. Provides static methods `getParser()` and `parse()`.
+- **`src/parser.js`**: Core parsing engine that orchestrates all parsers and returns structured results.
+- **`src/parser-browsers.js`**: Browser detection logic using regex patterns.
+- **`src/parser-os.js`**: Operating system detection logic.
+- **`src/parser-platforms.js`**: Platform type detection (desktop, tablet, mobile).
+- **`src/parser-engines.js`**: Rendering engine detection (WebKit, Blink, Gecko, etc.).
+- **`src/constants.js`**: Centralized constants including browser aliases and mappings.
+- **`src/utils.js`**: Utility functions for string matching and manipulation.
+
+### Build Output
+
+- **`es5.js`**: ES5 transpiled version (default export).
+- **`bundled.js`**: ES5 version with babel-polyfill included.
+
+## Development Workflow
+
+### Setup
+
+```bash
+npm install
+```
+
+### Key Commands
+
+- **Build**: `npm run build` - Compiles source files using Webpack and Babel.
+- **Test**: `npm test` - Runs unit and acceptance tests using AVA.
+- **Lint**: `npm run lint:check` - Checks code style using ESLint.
+- **Lint Fix**: `npm run lint:fix` - Auto-fixes linting issues.
+- **Watch Mode**: `npm run watch` - Builds on file changes.
+- **Test Watch**: `npm run test:watch` - Runs tests on file changes.
+
+### Testing
+
+- Tests are located in `test/acceptance/` and `test/unit/`.
+- Acceptance tests use real User-Agent strings from `test/acceptance/useragentstrings.yml`.
+- Always update `useragentstrings.yml` when adding browser support.
+- Test framework: AVA with Babel integration.
+
+## Coding Standards
+
+### Style Guide
+
+- **ESLint Config**: Based on Airbnb Base style guide.
+- **Parser**: Uses `babel-eslint`.
+- **Exceptions**:
+  - Underscore-dangle allowed for private properties.
+  - `no-void` disabled.
+  - ES6 imports must include `.js` extension.
+
+### Naming Conventions
+
+- **Browser Aliases**: Use lowercase letters, replace spaces/dashes with underscores, drop "browser" suffix.
+  - Examples: `Opera Coast` → `opera_coast`, `UC Browser` → `uc`, `SeaMonkey` → `seamonkey`.
+- **Private Properties**: Prefix with underscore (e.g., `_ua`).
+- **Constants**: Use `UPPER_SNAKE_CASE` for constant maps and aliases.
+
+### Code Patterns
+
+- Use ES6 modules with explicit `.js` extensions.
+- Prefer static methods in Bowser class.
+- Use class-based structure for Parser.
+- Regex patterns should be well-documented and tested.
+- Keep parsers modular and focused on single responsibility.
+
+## Adding Browser Support
+
+When adding support for a new browser:
+
+1. Add regex pattern to `src/parser-browsers.js`.
+2. Add browser name to `BROWSER_ALIASES_MAP` in `src/constants.js`.
+3. Add corresponding entry to `BROWSER_MAP`.
+4. Add test cases to `test/acceptance/useragentstrings.yml`.
+5. Run tests to verify: `npm test`.
+6. Check for duplicates before adding aliases.
+
+## Branching Strategy
+
+- **`master`**: Development branch.
+- **`production`**: Production branch.
+- **New Features**: Branch from `master`, PR back to `master`.
+- **Hot-fixes/Browser Support**: Branch from `production`, PR back to `production`.
+
+## Important Files
+
+- **`index.d.ts`**: TypeScript definitions.
+- **`.babelrc`**: Babel configuration for ES5 transpilation.
+- **`webpack.config.js`**: Build configuration.
+- **`.eslintrc.yml`**: Linting rules.
+- **`package.json`**: Dependencies and scripts.
+
+## API Design Principles
+
+- Keep the API simple and intuitive.
+- Bowser class should be stateless and provide factory methods.
+- Parser class handles instance-specific logic.
+- Results should be structured and predictable.
+- Support both immediate parsing and lazy parsing.
+
+## Performance Considerations
+
+- Parsers use lazy evaluation where possible.
+- Regex patterns are optimized for common browsers first.
+- Optional `skipParsing` parameter for delayed parsing.
+- Minimal bundle size is a priority (~4.8kB gzipped).
+
+## Documentation
+
+- Use JSDoc comments for all public APIs.
+- Document parameters, return types, and provide examples.
+- Update README.md for API changes.
+- Generate docs with: `npm run generate-docs`.
+
+## Common Pitfalls
+
+- Always check `BROWSER_ALIASES_MAP` for existing aliases before adding new ones.
+- User-Agent strings can be complex; test edge cases thoroughly.
+- Remember to update both the alias map and the reverse map in constants.
+- Browser versions should be treated as strings, not numbers.
+- Keep regex patterns readable with comments explaining their purpose.