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

tests/integration/find-*.test.ts and tests/unit/brainy/find*.test.ts each
opened one or more Brainy instances (via beforeAll/beforeEach) and never
closed them — the leaked instance's cadence timer stays armed for the rest
of the single-forked vitest run and keeps narrating into every later file.

find-unified-integration.test.ts was a real bug, not just a missing hook:
its afterAll called a no-op TestCleanup().cleanup() (nothing was ever
registered with it) and then discarded the brain reference with
`brain = null` — the brain was never actually closed.

tests/integration/find-orderby-every-path.test.ts

@@ -40,7 +40,7 @@
  * the covering is ASSERTED from the leg's own output rather than assumed. This
  * pin is about ordering, and it says nothing about recall.
  */
-import { describe, it, expect, beforeAll } from 'vitest'
+import { describe, it, expect, beforeAll, afterAll } from 'vitest'
 import { Brainy } from '../../src/brainy'
 import { NounType, VerbType } from '../../src/types/graphTypes'
 import { resolveEntityId } from '../../src/utils/idNormalization'
@@ -107,6 +107,10 @@ describe('find(): orderBy is the order on every path', () => {
     }
   })
 
+  afterAll(async () => {
+    await brain.close()
+  })
+
   it('the fixture: the hybrid candidate set covers the whole filter universe', async () => {
     const universe: string[] = await (brain as any).filterIdsBelted({ lane: 'alpha' })
     expect(universe).toHaveLength(ROWS)