• Add full collection REST API with CRUD operations for collections and items
• Implement collection models, handlers, and database integration with SQLite/PostgreSQL support
• Add collection endpoints: GET/POST/PUT/DELETE for collections and collection items
• Fix critical server enhancement bug by consolidating to engine.DatabaseClient
• Remove obsolete content.DatabaseClient that lacked collection support
• Enable proper collection reconstruction during server-side enhancement
• Collections now persist correctly and display new items after API modifications
Joakim
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