Initialize composer project for WooCommerce Licensed Product Client

- Set up composer.json with package metadata and PSR-4 autoloading
- Add symfony/http-client ^7.0 as HTTP client dependency
- Create project structure (src/, tests/, tmp/)
- Add README.md with project overview
- Add CHANGELOG.md to track version history
- Add .gitignore for vendor and cache files
- Include OpenAPI specification in tmp/openapi.json

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,9 @@
+/vendor/
+.phpunit.result.cache
+.php-cs-fixer.cache
+*.log
+.DS_Store
+.idea/
+.vscode/
+*.swp
+*.swo