**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.

tests/setup.ts

@@ -0,0 +1,33 @@
+/**
+ * Simple test setup for Brainy library
+ * No direct TensorFlow references - patches are handled internally by Brainy
+ */
+
+import { beforeEach } from 'vitest'
+
+// Clean up between tests
+beforeEach(() => {
+  // Clear any global state that might interfere with tests
+  if (typeof global !== 'undefined' && global.__ENV__) {
+    delete global.__ENV__
+  }
+})
+
+// Simple test utilities focused on Brainy usage patterns
+declare global {
+  let testUtils: {
+    createTestVector: (dimensions: number) => number[]
+    timeout: number
+  }
+}
+
+// Add simple test utilities
+globalThis.testUtils = {
+  // Create a simple test vector with predictable values
+  createTestVector: (dimensions: number): number[] => {
+    return Array.from({ length: dimensions }, (_, i) => (i + 1) / dimensions)
+  },
+
+  // Standard timeout for async operations
+  timeout: 30000
+}