**test(tests): enhance test clarity, isolation, and robustness**

- **Test Improvements**:
  - Introduced data-clearing steps (`.clear()`) across critical test cases for ensuring better test isolation and preventing state leakage.
  - Extended support for overriding global utilities (`testUtils`) and added fallback behaviors for test vector creation.

- **Configuration Updates**:
  - Added support for `distanceFunction` as an alternative to `metric` in vector operations for consistency.
  - Adjusted and unified asynchronous `timeout` handling across test suites for predictability.

- **Purpose**:
  - These updates improve reliability, maintainability, and clarity in test cases while ensuring compatibility across diverse test environments.

tests/setup.ts

@@ -5,6 +5,17 @@
 
 import { beforeEach } from 'vitest'
 
+// Extend global type definitions
+declare global {
+  let testUtils:
+    | {
+        createTestVector: (dimensions: number) => number[]
+        timeout: number
+      }
+    | undefined
+  let __ENV__: any
+}
+
 // Clean up between tests
 beforeEach(() => {
   // Clear any global state that might interfere with tests
@@ -13,16 +24,8 @@ beforeEach(() => {
   }
 })
 
-// Simple test utilities focused on Brainy usage patterns
-declare global {
-  let testUtils: {
-    createTestVector: (dimensions: number) => number[]
-    timeout: number
-  }
-}
-
 // Add simple test utilities
-globalThis.testUtils = {
+global.testUtils = {
   // Create a simple test vector with predictable values
   createTestVector: (dimensions: number): number[] => {
     return Array.from({ length: dimensions }, (_, i) => (i + 1) / dimensions)