Database Schema Designer

Design a relational database schema for [PROJECT_DESCRIPTION]. The system must support the following core use cases: [USE_CASE_LIST]. Use [DATABASE_TYPE — e.g., PostgreSQL, MySQL] conventions. For each table, specify: table name, all columns with data types and constraints (PRIMARY KEY, NOT NULL, UNIQUE, FOREIGN KEY), and a brief comment explaining the table's purpose. Define all foreign key relationships and indicate whether each is one-to-one, one-to-many, or many-to-many. Include appropriate indexes for columns that will be frequently filtered or joined. Identify any junction tables needed for many-to-many relationships. Output the schema as valid SQL CREATE TABLE statements followed by a plain-English Entity-Relationship summary. Flag any design decisions that involve trade-offs and explain your rationale.