Review this schema design

Before you create the tables everyone will depend on for years.

Critique the schema below as someone who will have to query it daily and migrate it in two years.

Cover:
1. **Normalisation**: what is duplicated, and where denormalisation is a deliberate good choice rather than an accident.
2. **Keys**: is the primary key stable and meaningful? Are natural keys being used where a surrogate would survive better?
3. **Types**: anything stored as text that should be typed, money stored as float, timestamps without timezone, booleans encoded as strings or nullable.
4. **Nullability**: every nullable column where NULL has no clear meaning, and every NOT NULL with a placeholder default standing in for missing.
5. **Constraints**: missing foreign keys, missing unique constraints, invariants enforced only in application code.
6. **Growth**: which table gets large first, and what breaks when it does.

Give me the three changes worth making now and the ones that can wait. Be decisive.

Schema:

Schema and data quality. Designing tables, migrating them without breaking live code, and cleaning what you have been handed.