[suguanYang]

Summary

Revert PR #491 at the user's request and restore DOCX parsing to the v1.2.41 implementation.

 DOCX parser
-remove optional relationship-part compatibility
+restore the previous relationship-part read

Evidence

• Before: PR fix(parser): support DOCX packages without document relationships #491 was merged and v1.2.42 was published.
• After: The production workflow was cancelled before deployment, v1.2.42 was withdrawn to draft, and v1.2.41 was restored as the latest published release.
• Live production still uses API task definition 73 and worker task definition 69, with both services healthy at 2/2 tasks.
• The reverted parser and test paths match v1.2.41 exactly.

Deployment Notes

No production rollout is required: the attempted release was stopped before ECS services changed. This PR restores main to the previous implementation. No schema or configuration changes.

Merge Danger

Door: Two-way; revert this rollback to reintroduce the fix after the deployment scope is agreed.

Blast Radius: DOCX parsing. The previous missing-relationship-file behavior is intentionally restored.