Add custom instructions (#7047)

Author: alexr00

.github/copilot-instructions.md

@@ -0,0 +1,17 @@
+## General Guidelines
+- **Follow the existing code style**: Use single quotes, semicolons, and 2-space indentation. See `.eslintrc.base.json` for detailed linting rules.
+- **TypeScript**: Use modern TypeScript features. Prefer explicit types where clarity is needed, but do not over-annotate.
+- **React/JSX**: Webviews use React-style JSX with custom factories (`vscpp`, `vscppf`).
+- **Strictness**: Some strictness is disabled in `tsconfig.base.json` (e.g., `strictNullChecks: false`), but new code should avoid unsafe patterns.
+- **Testing**: Place tests under `src/test`. Do not include test code in production files.
+- **Localization**: Use `%key%` syntax for strings that require localization. See `package.nls.json`.
+
+## Extension-Specific Practices
+- **VS Code API**: Use the official VS Code API for all extension points. Register commands, views, and menus via `package.json`.
+- **Configuration**: All user-facing settings must be declared in `package.json` under `contributes.configuration`.
+- **Activation Events**: Only add new activation events if absolutely necessary.
+- **Webviews**: Place webview code in the `webviews/` directory. Use the shared `common/` code where possible.
+- **Commands**: Register new commands in `package.json` and implement them in `src/commands.ts` or a relevant module.
+
+---
+_Last updated: 2025-06-20_