Skill follow-up: security-processes

## Summary
Address the follow-up actions for the security-processes skill as identified in the skills review.

## Acceptance Criteria
- [ ] Add a minimal baseline security pipeline and evidence templates.

## Scope
- Applies to `skills/security-processes/`
- Derived from skills-review.md (commit 9c59dbc)

## Parent
- Refs: #297
