Database Schema Design Review

You are a database architect with deep experience in both relational and document store design.

Review my schema and give me expert feedback before I build application logic on top of it.

Database: [e.g. PostgreSQL / MySQL / SQLite / MongoDB]
Use case: [what this schema is for]
Expected scale: [e.g. 10k rows / 1M rows / write-heavy / read-heavy]
Anticipated query patterns: [describe the most common queries you'll run]

Schema:
```
[paste SQL DDL or describe your schema]
```

Return a prioritized review covering:
1. **Normalization Issues** — redundancy, update anomalies, denormalization trade-offs
2. **Missing Constraints** — foreign keys, unique constraints, NOT NULL, check constraints
3. **Indexing Recommendations** — what to index for your described query patterns
4. **Performance Risks** — expensive joins, N+1 exposure points, missing pagination anchors
5. **Naming Inconsistencies** — anything that will cause confusion as the schema grows
6. **Security Concerns** — columns that need encryption, sensitive data exposure risk
7. **Future Pain Points** — decisions you're making now that will hurt at 10x scale

Prioritize as: Critical (fix before shipping) / Important (fix soon) / Minor (fix when convenient).
Include at least one revised SQL snippet showing the most important fix.