[codex] Sync local uploads into backend CDE files

[ActiveInAI]

Summary

• Sync module file uploads into the backend CDE file API when the current folder is backend-writable.
• Persist source checksums on module CDE file create and refresh checksums when file content is replaced.
• Deduplicate local-upload nodes against backend CDE metadata by module, parent, name, size, and checksum so refresh does not show duplicates.
• Document the checksum field in the OpenAPI/module file integration contract.

Validation

• bun run test -- lib/module-file-api-client.test.ts lib/business-workflow.test.ts
• bun run test
• bun run typecheck
• bun run lint
• bun run build
• cargo fmt --check
• cargo check -p architoken-harness-core
• cargo test -p architoken-harness-core module_files
• cargo test -p architoken-harness-core
• python3 tools/production_readiness_contract.py
• Local runtime smoke: create/list/update/trash module CDE file with checksum; /app/modules and /app/modules/digital_twin return 200; /app/digital-twin returns 404.