Add NDK skill documentation and examples

- Introduced comprehensive documentation for the Nostr Development Kit (NDK) including an overview, quick reference, and troubleshooting guide.
- Added detailed examples covering initialization, authentication, event publishing, querying, and user profile management.
- Structured the documentation to facilitate quick lookups and deep learning, based on real-world usage patterns from the Plebeian Market application.
- Created an index for examples to enhance usability and navigation.
- Bumped version to 1.0.0 to reflect the addition of this new skill set.

.claude/skills/ndk/README.md

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+# NDK (Nostr Development Kit) Claude Skill
+
+This skill provides comprehensive knowledge about working with the Nostr Development Kit (NDK) library.
+
+## Files
+
+- **ndk-skill.md** - Complete reference documentation with patterns from production usage
+- **quick-reference.md** - Quick lookup guide for common NDK tasks
+- **examples/** - Code examples extracted from the Plebeian Market codebase
+
+## Usage
+
+When working with NDK-related code, reference these documents to:
+- Understand initialization patterns
+- Learn authentication flows (NIP-07, NIP-46, private keys)
+- Implement event creation and publishing
+- Set up subscriptions for real-time updates
+- Query events with filters
+- Handle users and profiles
+- Integrate with TanStack Query
+
+## Key Topics Covered
+
+1. NDK Initialization & Configuration
+2. Authentication & Signers
+3. Event Creation & Publishing
+4. Querying Events
+5. Real-time Subscriptions
+6. User & Profile Management
+7. Tag Handling
+8. Replaceable Events
+9. Relay Management
+10. Integration with React/TanStack Query
+11. Error Handling & Best Practices
+12. Performance Optimization
+
+All examples are based on real production code from the Plebeian Market application.
+