Refactor to focused n8n node documentation MCP server

Major refactoring to align with actual requirements:
- Purpose: Serve n8n node code/documentation to AI agents only
- No workflow execution or management features
- Complete node information including source code, docs, and examples

New features:
- Node documentation service with SQLite FTS5 search
- Documentation fetcher from n8n-docs repository
- Example workflow generator for each node type
- Simplified MCP tools focused on node information
- Complete database rebuild with all node data

MCP Tools:
- list_nodes: List available nodes
- get_node_info: Get complete node information
- search_nodes: Full-text search across nodes
- get_node_example: Get usage examples
- get_node_source_code: Get source code only
- get_node_documentation: Get documentation only
- rebuild_database: Rebuild entire database
- get_database_statistics: Database stats

Database schema includes:
- Node source code and metadata
- Official documentation from n8n-docs
- Generated usage examples
- Full-text search capabilities
- Category and type filtering

Updated README with:
- Clear purpose statement
- Claude Desktop installation instructions
- Complete tool documentation
- Troubleshooting guide

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

.gitignore

@@ -64,4 +64,4 @@ docker-compose.override.yml
 .lock-wscript
 .node_repl_history
 .npmrc
-.yarnrc
+.yarnrctemp/