Expand the development guide from a minimal overview into a
comprehensive reference covering:
- Code standards: single responsibility, control flow, input
validation, promise handling, and variable scoping
- Security section: treat all external input as malicious, use
path.join over string concatenation, no secrets in code
- Reorganize publication steps to include version bump before
build/publish for a logical workflow
- Add project context note clarifying the scaffolding role of
@zen/start