Prepare the FreeCAD Addon Manager submission checklist

[Jayktopus]

Goal

Identify and close the packaging gaps before proposing Scan2Sketch to the official FreeCAD Addon Index.

Scope

• Review package.xml and repository structure against current official requirements.
• Document how optional Python environments and model weights should be handled.
• Verify licence metadata and third-party notices.
• Define a clean-install acceptance test.

Acceptance criteria

• Checklist links to current official FreeCAD sources.
• Blocking and non-blocking gaps are separated.
• No submission is made until the clean-install test passes.