Ability to reuse activities and content elements across repositories

[underscope]

Key Features

• Cross-Repository Linking: Activities and their content elements can be linked from library repositories into course repositories
• Hierarchical Linking: Linking an activity automatically links its entire subtree (children, grandchildren, and all content elements)
• Auto-Sync Updates: When source content is modified, all linked copies automatically receive updates via SSE propagation
• Detach on Edit: Editing a linked copy automatically breaks the link ("if you edit it, you own it"), converting it to an independent local copy while preserving source provenance
• Cross-Schema Type Mapping: Library items can transform to compatible types when linked to repositories with different schemas (e.g., ITEM → PAGE via mapsTo config)
• UI cues for linked activities & linked content elements