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

skills/projection-patterns/SKILL.md

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+---
+name: projection-patterns
+description: Build read models and projections from event streams. Use when implementing CQRS read sides, building materialized views, or optimizing query performance in event-sourced systems.
+---
+
+# Projection Patterns
+
+Comprehensive guide to building projections and read models for event-sourced systems.
+
+## Use this skill when
+
+- Building CQRS read models
+- Creating materialized views from events
+- Optimizing query performance
+- Implementing real-time dashboards
+- Building search indexes from events
+- Aggregating data across streams
+
+## Do not use this skill when
+
+- The task is unrelated to projection patterns
+- 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.