test(hygiene): close every brain the integration suite creates

Each file opened a Brainy in beforeAll/beforeEach (or a single it()) and
never closed it. related-verb-array.test.ts and vfs-containment-batched.test.ts
were real bugs: their afterAll discarded the brain with `brain = null as any`
without ever calling close() first.

tests/integration/entity-confidence-weight.test.ts

@@ -7,7 +7,7 @@
  * - Backward compatibility preserved
  */
 
-import { describe, it, expect, beforeEach } from 'vitest'
+import { describe, it, expect, beforeEach, afterEach } from 'vitest'
 import { Brainy } from '../../src/brainy.js'
 import { NounType } from '../../src/types/graphTypes.js'
 
@@ -19,6 +19,10 @@ describe('Entity Confidence & Weight Exposure', () => {
     await brain.init()
   })
 
+  afterEach(async () => {
+    await brain.close()
+  })
+
   describe('Entity interface', () => {
     it('should expose confidence when adding entity with confidence', async () => {
       const id = await brain.add({