feat(llm-application-dev): modernize to LangGraph and latest models v2.0.0

- Migrate from LangChain 0.x to LangChain 1.x/LangGraph patterns
- Update model references to Claude 4.5 and GPT-5.2
- Add Voyage AI as primary embedding recommendation
- Add structured outputs with Pydantic
- Replace deprecated initialize_agent() with StateGraph
- Fix security: use AST-based safe math instead of unsafe execution
- Add plugin.json and README.md for consistency
- Bump marketplace version to 1.3.3

plugins/llm-application-dev/README.md

@@ -0,0 +1,86 @@
+# LLM Application Development Plugin for Claude Code
+
+Build production-ready LLM applications, advanced RAG systems, and intelligent agents with modern AI patterns.
+
+## Version 2.0.0 Highlights
+
+- **LangGraph Integration**: Updated from deprecated LangChain patterns to LangGraph StateGraph workflows
+- **Modern Model Support**: Claude Opus/Sonnet/Haiku 4.5 and GPT-5.2/GPT-5.2-mini
+- **Voyage AI Embeddings**: Recommended embedding models for Claude applications
+- **Structured Outputs**: Pydantic-based structured output patterns
+
+## Features
+
+### Core Capabilities
+- **RAG Systems**: Production retrieval-augmented generation with hybrid search
+- **Vector Search**: Pinecone, Qdrant, Weaviate, Milvus, pgvector optimization
+- **Agent Architectures**: LangGraph-based agents with memory and tool use
+- **Prompt Engineering**: Advanced prompting techniques with model-specific optimization
+
+### Key Technologies
+- LangChain 1.x / LangGraph for agent workflows
+- Voyage AI, OpenAI, and open-source embedding models
+- HNSW, IVF, and Product Quantization index strategies
+- Async patterns with checkpointers for durable execution
+
+## Agents
+
+| Agent | Description |
+|-------|-------------|
+| `ai-engineer` | Production-grade LLM applications, RAG systems, and agent architectures |
+| `prompt-engineer` | Advanced prompting techniques, constitutional AI, and model optimization |
+| `vector-database-engineer` | Vector search implementation, embedding strategies, and semantic retrieval |
+
+## Skills
+
+| Skill | Description |
+|-------|-------------|
+| `langchain-architecture` | LangGraph StateGraph patterns, memory, and tool integration |
+| `rag-implementation` | RAG systems with hybrid search and reranking |
+| `llm-evaluation` | Evaluation frameworks for LLM applications |
+| `prompt-engineering-patterns` | Chain-of-thought, few-shot, and structured outputs |
+| `embedding-strategies` | Embedding model selection and optimization |
+| `similarity-search-patterns` | Vector similarity search implementation |
+| `vector-index-tuning` | HNSW, IVF, and quantization optimization |
+| `hybrid-search-implementation` | Vector + keyword search fusion |
+
+## Commands
+
+| Command | Description |
+|---------|-------------|
+| `/llm-application-dev:langchain-agent` | Create LangGraph-based agent |
+| `/llm-application-dev:ai-assistant` | Build AI assistant application |
+| `/llm-application-dev:prompt-optimize` | Optimize prompts for production |
+
+## Installation
+
+```bash
+claude --plugin-dir /path/to/llm-application-dev
+```
+
+Or copy to your project's `.claude-plugin/` directory.
+
+## Requirements
+
+- LangChain >= 1.2.0
+- LangGraph >= 0.3.0
+- Python 3.11+
+
+## Changelog
+
+### 2.0.0 (January 2026)
+- **Breaking**: Migrated from LangChain 0.x to LangChain 1.x/LangGraph
+- **Breaking**: Updated model references to Claude 4.5 and GPT-5.2
+- Added Voyage AI as primary embedding recommendation for Claude apps
+- Added LangGraph StateGraph patterns replacing deprecated `initialize_agent()`
+- Added structured outputs with Pydantic
+- Added async patterns with checkpointers
+- Fixed security issue: replaced unsafe code execution with AST-based safe math evaluation
+- Updated hybrid search with modern Pinecone client API
+
+### 1.2.2
+- Minor bug fixes and documentation updates
+
+## License
+
+MIT License - See the plugin configuration for details.