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

skills/risk-metrics-calculation/SKILL.md

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+---
+name: risk-metrics-calculation
+description: Calculate portfolio risk metrics including VaR, CVaR, Sharpe, Sortino, and drawdown analysis. Use when measuring portfolio risk, implementing risk limits, or building risk monitoring systems.
+---
+
+# Risk Metrics Calculation
+
+Comprehensive risk measurement toolkit for portfolio management, including Value at Risk, Expected Shortfall, and drawdown analysis.
+
+## Use this skill when
+
+- Measuring portfolio risk
+- Implementing risk limits
+- Building risk dashboards
+- Calculating risk-adjusted returns
+- Setting position sizes
+- Regulatory reporting
+
+## Do not use this skill when
+
+- The task is unrelated to risk metrics calculation
+- 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.