chore: release v4.0.0 - sync 550+ skills and restructure docs

skills/threat-mitigation-mapping/SKILL.md

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+---
+name: threat-mitigation-mapping
+description: Map identified threats to appropriate security controls and mitigations. Use when prioritizing security investments, creating remediation plans, or validating control effectiveness.
+---
+
+# Threat Mitigation Mapping
+
+Connect threats to controls for effective security planning.
+
+## Use this skill when
+
+- Prioritizing security investments
+- Creating remediation roadmaps
+- Validating control coverage
+- Designing defense-in-depth
+- Security architecture review
+- Risk treatment planning
+
+## Do not use this skill when
+
+- The task is unrelated to threat mitigation mapping
+- You need a different domain or tool outside this scope
+
+## Instructions
+
+- Clarify goals, constraints, and required inputs.
+- Apply relevant best practices and validate outcomes.
+- Provide actionable steps and verification.
+- If detailed examples are required, open `resources/implementation-playbook.md`.
+
+## Resources
+
+- `resources/implementation-playbook.md` for detailed patterns and examples.