Add get_node_relations function for efficient graph traversal

[enthali]

Summary

This PR adds a new get_node_relations function to the MCP memory server that enables efficient graph traversal by retrieving all incoming and outgoing relations for a specific node without loading the entire graph.

Changes

• New function: getNodeRelations in KnowledgeGraphManager class
• New MCP tool: get_node_relations exposed via the server API
• Documentation: Updated README.md with API documentation for the new function
• Tool registration: Added to .github/mcp.json for discoverability

Implementation Details

Input

• nodeName (string): The name of the entity to get relations for

Output

• outgoing (array): Relations where this node is the source
• incoming (array): Relations where this node is the target
• connected_entities (string[]): Names of all connected entities

Use Cases

• Graph traversal without loading entire graph
• Finding connected entities efficiently
• Building relationship maps for specific nodes
• Performance optimization for large knowledge graphs

Testing

The implementation has been tested locally with:

• Existing nodes with multiple relations
• Nodes with no relations (returns empty arrays)
• Non-existent nodes (returns empty structure)

Files Changed

• src/memory/index.ts: Core implementation
• src/memory/README.md: API documentation

This enhancement maintains backward compatibility and follows existing code patterns in the memory server.