[codex] Bind local previews to hydrated backend CDE files

[ActiveInAI]

Summary

• Bind local preview metadata onto an existing backend CDE file node when backend metadata hydrates before the local upload index.
• Match backend/local records by module, parent, filename, size, and checksum so the CDE workbench keeps one canonical row while still enabling local lightweight preview.
• Add a frontend adapter contract test for the backend-first hydration order.

Root Cause

The previous upload/metadata dedupe handled the local-first order. After a refresh, backend CDE nodes can hydrate first and the local upload index can hydrate later; in that order the adapter could add a second local-upload row instead of enriching the backend row with preview metadata.

Validation

• bun run test -- lib/business-workflow.test.ts
• bun run test
• bun run typecheck
• bun run lint
• bun run build
• python3 tools/production_readiness_contract.py