Design an optimized database schema with proper relationships, indexes, and migration scripts.
Design a complete database schema for [Application Type] application. Use [MySQL/PostgreSQL/MongoDB]. Requirements: [Describe your application requirements, main entities, and relationships] Provide: 1. Entity-Relationship diagram (text format) 2. Complete table/collection definitions 3. Data types and constraints 4. Primary and foreign keys 5. Indexes (explain reasoning for each) 6. Normalization level (1NF/2NF/3NF) reasoning 7. Many-to-many junction tables 8. Audit/timestamp fields 9. Soft delete strategy 10. Migration scripts (SQL/NoSQL) 11. Sample seed data 12. Common query examples 13. Scaling considerations 14. Backup strategy recommendation