feat(angular): Add metadata.json and README.md to all Angular skills

- Add metadata.json with version tracking, organization, and references
- Add README.md with skill overviews, usage guides, and quick references
- Brings Angular skills to parity with React Best Practices infrastructure
- Covers: angular, angular-state-management, angular-ui-patterns, angular-best-practices

skills/angular-best-practices/README.md

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+# Angular Best Practices
+
+Performance optimization and best practices for Angular applications optimized for AI agents and LLMs.
+
+## Overview
+
+This skill provides prioritized performance guidelines across:
+
+- **Change Detection** - OnPush strategy, Signals, Zoneless apps
+- **Async Operations** - Avoiding waterfalls, SSR preloading
+- **Bundle Optimization** - Lazy loading, `@defer`, tree-shaking
+- **Rendering Performance** - TrackBy, virtual scrolling, CDK
+- **SSR & Hydration** - Server-side rendering patterns
+- **Template Optimization** - Structural directives, pipe memoization
+- **State Management** - Efficient reactivity patterns
+- **Memory Management** - Subscription cleanup, detached refs
+
+## Structure
+
+The `SKILL.md` file is organized by priority:
+
+1. **Critical Priority** - Largest performance gains (change detection, async)
+2. **High Priority** - Significant impact (bundles, rendering)
+3. **Medium Priority** - Noticeable improvements (SSR, templates)
+4. **Low Priority** - Incremental gains (memory, cleanup)
+
+Each rule includes:
+
+- ❌ **WRONG** - What not to do
+- ✅ **CORRECT** - Recommended pattern
+- 📝 **Why** - Explanation of the impact
+
+## Quick Reference Checklist
+
+**For New Components:**
+
+- [ ] Using `ChangeDetectionStrategy.OnPush`
+- [ ] Using Signals for reactive state
+- [ ] Using `@defer` for non-critical content
+- [ ] Using `trackBy` for `*ngFor` loops
+- [ ] No subscriptions without cleanup
+
+**For Performance Reviews:**
+
+- [ ] No async waterfalls (parallel data fetching)
+- [ ] Routes lazy-loaded
+- [ ] Large libraries code-split
+- [ ] Images use `NgOptimizedImage`
+
+## Version
+
+Current version: 1.0.0 (February 2026)
+
+## References
+
+- [Angular Performance](https://angular.dev/guide/performance)
+- [Zoneless Angular](https://angular.dev/guide/zoneless)
+- [Angular SSR](https://angular.dev/guide/ssr)