LangChain Agent - NEAR Social Poster

Description

Build a LangChain agent template for social poster on NEAR.

**THE VIRAL LOOP:**
User wants social poster agent → Uses template → Agent operates on NEAR

**Deliverables:**
1. Complete LangChain agent with tools
2. Configuration options
3. Example usage
4. Published to PyPI and GitHub

**Success Metric:** 20+ uses