test(enterprise): cover restart persistence recovery

[Gracker]

Summary

• Align SessionPersistenceService with the enterprise SQLite DB path so session state shares the same WAL-backed durable store as trace/report metadata.
• Add a route-level enterprise restart regression covering trace list, report load, recoverable session catalog, and persisted turns after in-memory state is cleared.
• Mark README §0.3.10 complete with the concrete regression file.

Verification

• cd backend && npx jest --runInBand --forceExit src/routes/tests/enterpriseRestartPersistence.test.ts src/routes/tests/enterpriseTraceMetadataRoutes.test.ts src/routes/tests/enterpriseReportRoutes.test.ts
• cd backend && npm run typecheck
• cd backend && npm run test:core
• git diff --check
• cd backend && npm run test:scene-trace-regression
• npm run verify:pr

Stacked on #81 / feature/enterprise-multi-tenant-secretstore-hardening.

[Gracker]

已通过 commit 67856ec (merge) + 023a84a (frontend rebuild) 合入 main，关闭此 PR。