feat(test): add comprehensive test suite and testing infrastructure

- Add vitest configuration with coverage reporting
- Create test setup file with DOM mocks
- Add tests for state management, helpers, and tool configurations
- Update tsconfig and package.json for testing support
- Clean up unused comments and improve code style

.gitignore

@@ -22,4 +22,7 @@ dist-ssr
 *.njsproj
 *.sln
 *.sw?
+# Coverage reports
+coverage/
+*.lcov