chore(test/helpers): delete 2 dead modules + colocate 18 unused exports

Deleted entire files (zero adopted consumers):
  - helpers/constants.mts (72 LOC, 7 TEST_* fixture constants)
  - helpers/cli-process-pool.mts (223 LOC, CliProcessPool class +
    cleanupProcessPool + getProcessPool — the pool was never adopted
    by tests, all spawn through executeCliInScratch instead)

Colocated (used only as internal signatures):
  - mock-auth.mts: MockAuthOptions, MockLoginOptions, MockTokenOptions,
    MockOrgOptions, simulateDelay
  - mock-malware-api.mts: ExtendedAlert, CompactSocketArtifactWithScore
  - sdk-test-helpers.mts: getMockHandleApiCall, getMockSetupSdk +
    delete setupSdkMockWithCustomSdk (entirely dead)
  - environment.mts: delete resetExitCode, setupTestWithCleanup
    (entirely dead) + drop now-unused afterEach import
  - test-fixtures.mts: delete createTempFixtures (entirely dead)

helpers/index.mts: drop the constants.mts barrel re-export.

Author: jdalton

packages/cli/test/helpers/cli-process-pool.mts

@@ -4,7 +4,7 @@
  *   management.
  */
 
-import { afterEach, beforeEach, vi } from 'vitest'
+import { beforeEach, vi } from 'vitest'
 
 /**
  * Clear all mocks manually.
@@ -13,13 +13,6 @@ export function clearAllMocks(): void {
   vi.clearAllMocks()
 }
 
-/**
- * Reset process.exitCode manually.
- */
-export function resetExitCode(): void {
-  process.exitCode = undefined
-}
-
 /**
  * Setup standard test environment with beforeEach hook Clears all mocks and
  * resets process.exitCode.
@@ -30,25 +23,3 @@ export function setupTestEnvironment(): void {
     process.exitCode = undefined
   })
 }
-
-/**
- * Setup and cleanup for a test with custom initialization.
- */
-export function setupTestWithCleanup(
-  setup?: () => void | Promise<void>,
-  cleanup?: () => void | Promise<void>,
-): void {
-  beforeEach(async () => {
-    vi.clearAllMocks()
-    process.exitCode = undefined
-    if (setup) {
-      await setup()
-    }
-  })
-
-  if (cleanup) {
-    afterEach(async () => {
-      await cleanup()
-    })
-  }
-}

packages/cli/test/helpers/constants.mts

@@ -4,7 +4,6 @@
  */
 
 export * from './cli-execution.mts'
-export * from './constants.mts'
 export * from './environment.mts'
 export * from './generate-report-test-helpers.mts'
 export * from './handle-test-helpers.mts'