📚 [P3-LOW] Add Architecture Decision Records (ADRs) #33
Description
Proposed Solution
Create docs/adr/ with decision records:
ADR Template
```markdown
ADR-001: Choice of PostgreSQL over MySQL
Status
Accepted
Context
Need to choose a relational database for OAuth server.
Decision
Use PostgreSQL.
Consequences
Positive
- Better JSON support
- Array columns
- Better full-text search
Negative
- Team less familiar with PostgreSQL
Alternatives Considered
- MySQL
- MongoDB
```
Key ADRs to Document
- ADR-001: PostgreSQL vs MySQL
- ADR-002: bcrypt vs argon2
- ADR-003: HS256 vs RS256 default
- ADR-004: In-memory vs Redis rate limiting
- ADR-005: Embedded templates vs external
Priority: P3 - Low | Effort: 2-3 hours