**test(tests): add comprehensive test suite for Brainy functionality**

- **New Tests Added**:
  - Introduced multiple test suites covering core functionalities (`core.test.ts`), vector operations (`vector-operations.test.ts`), Node.js environment (`environment.node.test.ts`), browser setup (`environment.browser.test.ts`), and TensorFlow.js-specific behaviors (`tensorflow-patch.test.ts`).
  - Added performance, scalability, and error-handling tests to ensure robust validation of vector addition, search, and text embedding functionalities.
  - Introduced setup utilities (`tests/setup.ts`) and standardized test utilities for creating predictable test cases.

- **Configuration**:
  - Created `vitest.config.ts` for custom test configurations, including support for modern test environments (`jsdom`, `happy-dom`) and extended timeouts for asynchronous operations.

- **Validation**:
  - Includes compatibility checks for TensorFlow.js imports and ensures proper handling of `TextEncoder`/`TextDecoder` in Node.js environments.

This commit significantly enhances the testing coverage and structure, ensuring Brainy functionality is robust, cross-platform, and aligned with evolving reliability standards.

vitest.config.ts

@@ -0,0 +1,39 @@
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    // Default configuration
+    globals: true,
+    setupFiles: ['./tests/setup.ts'],
+    testTimeout: 60000, // 60 seconds for TensorFlow operations
+    hookTimeout: 60000,
+    // Include test files
+    include: ['tests/**/*.{test,spec}.{js,ts}'],
+    // Exclude old test files
+    exclude: [
+      'node_modules/**',
+      'dist/**',
+      'scripts/**',
+      'examples/**',
+      'cli-package/**',
+      '*.js' // Exclude old JS test files in root
+    ],
+    // Add environment options to help with TextEncoder issues
+    environmentOptions: {
+      env: {
+        FORCE_PATCHED_PLATFORM: 'true'
+      }
+    }
+  },
+  // Resolve configuration for proper module handling
+  resolve: {
+    alias: {
+      '@': './src',
+      '@tests': './tests'
+    }
+  },
+  // Define different configurations for different environments
+  define: {
+    'process.env.NODE_ENV': '"test"'
+  }
+})