✨ Implement Core Document Upload Functionality

[ssw-yakshaver]

Requested by: @miichaelsmedley via YakShaver.ai 🦬
cc: @edkranz, @miichaelsmedley, @zacharykeeping, @adamcogan, @calumjs, @uly1

Hi Team!

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Pain

Reprioritize the development focus to ensure the core functionality of uploading a main document is operational. This feature will allow users to upload documents and have them visible in TipTap initially, with future visibility in OnlyOffice.

Acceptance Criteria

1. Users can upload a main document through the Northwind365 website.
2. Uploaded documents are visible in TipTap immediately after upload.
3. The system is prepared for future integration with OnlyOffice without significant rework.