[COLLABORATION] Link Microsoft 365 documents to topics #3199

Allow a topic owner to link a Microsoft 365 document instead of downloading and re-uploading it. Documents stored in SharePoint or OneDrive, including documents shared through Teams, should be available to the assistant in chats linked to that topic. Microsoft remains the source of truth.

When a linked document is retrieved, SEMOSS should check for source changes and use the current successfully validated revision, or clearly explain why it cannot retrieve it. Existing uploaded topic files remain supported.

Follow-up to #3089 and SEMOSS/semoss-ui#3709, which provide persistent uploaded topic files and their UI/chat integration.

• An authorized owner can link a supported SharePoint or OneDrive document without manually downloading/uploading it, and the assistant can read it from a linked topic chat.
• The reference remains after restart/redeploy using persistent Collaboration metadata and configured SEMOSS storage.
• Editing the source is reflected after Check for updates or the next successful linked-document retrieval; an unchanged file avoids a full content download.
• Removing the link preserves the Microsoft original, and existing uploaded-file workflows continue to work.

Initial synchronization is manual and on retrieval. Proactive scheduled/background or webhook/delta synchronization can follow using the same reference/refresh service if a refresh interval is required.