docs: add quality tooling documentation

Co-authored-by: benkutil <228373+benkutil@users.noreply.github.com>

Author: Copilot

QUALITY_TOOLING.md

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+# Quality Tooling
+
+This document describes the quality tooling setup for the project.
+
+## Overview
+
+The project uses a comprehensive quality testing system including:
+
+- **Pre-commit hooks** - Automatically check and fix code quality before commits
+- **Local testing scripts** - Run linting and validation on demand
+- **CI workflows** - Automated quality checks on every push and pull request
+
+## Tools
+
+### Linting Tools
+
+- **Prettier** - Code formatting for JavaScript, CSS, Nunjucks, HTML, Markdown, and JSON
+- **ESLint** - JavaScript linting
+- **Stylelint** - CSS linting
+
+### Testing Tools
+
+- **Pa11y** - Accessibility testing
+
+## Local Development
+
+### NPM Scripts
+
+All quality checks can be run locally using npm scripts:
+
+```bash
+# Run all linters
+npm run lint
+
+# Run individual linters
+npm run lint:format       # Prettier check
+npm run lint:format:fix   # Prettier auto-fix
+npm run lint:css          # Stylelint check
+npm run lint:css:fix      # Stylelint auto-fix
+npm run lint:js           # ESLint check
+npm run lint:js:fix       # ESLint auto-fix
+
+# Run tests
+npm test                  # Run linting and build
+npm run test:accessibility # Run Pa11y accessibility tests (requires running server)
+
+# Build
+npm run build             # Build the site
+npm run build:prod        # Build for production
+npm start                 # Start development server
+```
+
+### Pre-commit Hooks
+
+The project uses [Husky](https://typicode.github.io/husky/) and [lint-staged](https://github.com/okonet/lint-staged) to automatically lint and fix files before committing:
+
+- Runs ESLint and fixes JavaScript files
+- Runs Stylelint and fixes CSS files
+- Runs Prettier and formats all supported files
+
+This ensures that all committed code meets quality standards.
+
+## CI Workflows
+
+### Quality Checks Workflow
+
+**File:** `.github/workflows/quality.yml`
+
+Runs on every push and pull request to main/master branches:
+
+1. Runs Prettier formatting check
+2. Runs Stylelint CSS linting
+3. Runs ESLint JavaScript linting
+4. Builds the site with Eleventy
+5. Uploads build artifacts
+
+### Accessibility Tests Workflow
+
+**File:** `.github/workflows/accessibility.yml`
+
+Runs on every push and pull request to main/master branches:
+
+1. Builds the site
+2. Starts a local server
+3. Runs Pa11y accessibility tests
+
+## Configuration Files
+
+- `.prettierrc` - Prettier configuration
+- `.prettierignore` - Files to exclude from Prettier
+- `eslint.config.js` - ESLint configuration (ESLint v9 flat config)
+- `.stylelintrc.json` - Stylelint configuration
+- `.lintstagedrc.json` - lint-staged configuration
+- `.pa11yci.json` - Pa11y configuration
+- `.husky/pre-commit` - Pre-commit hook script
+
+## Troubleshooting
+
+### ESLint Warning
+
+You may see a warning about module type when running ESLint. This is expected and doesn't affect functionality. The warning can be silenced by adding `"type": "module"` to package.json, but this may affect other parts of the build.
+
+### Pa11y in CI
+
+Pa11y requires Chrome to run. In CI environments, it needs the `--no-sandbox` flag, which is configured in `.pa11yci.json`.
+
+### Accessibility Tests
+
+To run accessibility tests locally:
+
+1. Build the site: `npm run build`
+2. Start a server: `npx serve _site -l 8080` (in background)
+3. Run tests: `npm run test:accessibility`