docs: Add Architecture Decision Records (ADRs) #37
Description
Summary
Document key architectural decisions and their rationale.
Proposed ADRs
- ADR-001: Zero-dependency core library design
- ADR-002: Lock-free metrics collection
- ADR-003: Builder pattern for configuration
- ADR-004: Feature flag decomposition
- ADR-005: DataSource trait abstraction
Format
Follow standard ADR template with context, decision, and consequences.
Benefits
- Onboard new contributors faster
- Preserve decision context
- Guide future development