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-state-management/README.md

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+# Angular State Management
+
+Complete state management patterns for Angular applications optimized for AI agents and LLMs.
+
+## Overview
+
+This skill provides decision frameworks and implementation patterns for:
+
+- **Signal-based Services** - Lightweight state for shared data
+- **NgRx SignalStore** - Feature-scoped state with computed values
+- **NgRx Store** - Enterprise-scale global state management
+- **RxJS ComponentStore** - Reactive component-level state
+- **Forms State** - Reactive and template-driven form patterns
+
+## Structure
+
+The `SKILL.md` file is organized into:
+
+1. **State Categories** - Local, shared, global, server, URL, and form state
+2. **Selection Criteria** - Decision trees for choosing the right solution
+3. **Implementation Patterns** - Complete examples for each approach
+4. **Migration Guides** - Moving from BehaviorSubject to Signals
+5. **Bridging Patterns** - Integrating Signals with RxJS
+
+## When to Use Each Pattern
+
+- **Signal Service**: Shared UI state (theme, user preferences)
+- **NgRx SignalStore**: Feature state with computed values
+- **NgRx Store**: Complex cross-feature dependencies
+- **ComponentStore**: Component-scoped async operations
+- **Reactive Forms**: Form state with validation
+
+## Version
+
+Current version: 1.0.0 (February 2026)
+
+## References
+
+- [Angular Signals](https://angular.dev/guide/signals)
+- [NgRx](https://ngrx.io)
+- [NgRx SignalStore](https://ngrx.io/guide/signals)