test(enterprise): verify D9 restart recovery

[Gracker]

Summary

• add D9 to the enterprise multi-window regression script
• simulate backend restart with a file-backed SQLite close/reopen path
• verify pending/running runs fail with recovery metadata, terminal runs remain completed, persisted AgentEvents replay, and trace metadata remains readable
• mark README §0.7 D9 complete

Base

• Stacked on test(enterprise): verify D8 provider snapshot #106 / feature/enterprise-multi-tenant-d8-provider-snapshot

Verification

• cd backend && npx jest --runInBand --forceExit src/scripts/tests/verifyEnterpriseMultiTenantWindows.test.ts
• cd backend && npx jest --runInBand --forceExit src/services/tests/analysisRunStore.test.ts src/services/tests/agentEventStore.test.ts src/routes/tests/enterpriseRestartPersistence.test.ts
• cd backend && npm run typecheck
• git diff --check
• npm run verify:pr