test(history): measure packed heap usage

vitest.web.perf.config.ts

@@ -1,5 +1,6 @@
 import { defineConfig } from 'vitest/config'
 import webConfig from './vitest.web.config.ts'
+import { vitestExecArgv } from './vitest.shared.ts'
 
 // Manual high-cardinality diagnostics stay outside every default Vitest
 // inventory and therefore outside CI's executed test lanes.
@@ -7,6 +8,8 @@ export default defineConfig({
   ...webConfig,
   test: {
     ...webConfig.test,
+    // Memory diagnostics use forced-GC baselines only in this manual inventory.
+    execArgv: [...vitestExecArgv, '--expose-gc'],
     include: [
       'apps/web/tests/**/*.perf.ts',
       'packages/api/session-controller/tests/**/*.perf.client.ts',